UCL University College London Eprints
UCL Eprints collects the work of UCL researchers and makes it freely available over the web, helping the worldwide scholarly community to discover UCL research. Institutional repositories like UCL Eprints complement the traditional academic publishing and scholarly communications processes. They raise the visibility of research and help to maximise its impact. UCL researchers are encouraged to deposit a copy of each journal article, conference paper, working paper, and any other research output, in the UCL Eprints at the earliest opportunity, ensuring that their research reaches as wide an audience as possible.
Culture of primary ciliary dyskinesia epithelial cells at air-liquid interface can alter ciliary phenotype but remains a robust and informative diagnostic aid. - Hirst, RA; Jackson, CL; Coles, JL; Williams, G; Rutman, A; Goggin, PM; Adam, EC; Page, A; Evans, HJ; Lackie, PM; O'Callaghan, C; Lucas, JS
The diagnosis of primary ciliary dyskinesia (PCD) requires the analysis of ciliary function and ultrastructure. Diagnosis can be complicated by secondary effects on cilia such as damage during sampling, local inflammation or recent infection. To differentiate primary from secondary abnormalities, re-analysis of cilia following culture and re-differentiation of epithelial cells at an air-liquid interface (ALI) aids the diagnosis of PCD. However changes in ciliary beat pattern of cilia following epithelial cell culture has previously been described, which has brought the robustness of this method into question. This is the first systematic study to evaluate ALI culture as an aid to...
Primary ciliary dyskinesia - Djakow, J; O'Callaghan, C
Primary ciliary dyskinesia (PCD) is a rare heterogeneous genetic disorder affecting ciliary function. Genes coding for various ciliary structural proteins or cytoplasmic proteins responsible for the assembly of cilia can be mutated resulting in abnormal ciliary function. However, despite the diversity of genotypes that can cause PCD the clinical phenotypes of PCD are all remarkably similar. The main clinical symptoms are caused by a lack of mucociliary clearance. Worryingly many patients are diagnosed late despite their classical, lifelong symptoms of a daily wet sounding cough and rhinosinusitis. Even when PCD is suspected, poor access to specialist diagnostic centres may delay...
Nebulization of corticosteroids to asthmatic children: Large variation in dose inhaled. - O'Callaghan, C; White, JA; Kantar, A
Despite problems associated with assessing the clinical effect and side effects of nebulized corticosteroids, little is known of the amount of drug that is inhaled by children with asthma or how this is affected by different drug formulations. The aim of this study was to test the hypothesis that children with asthma inhale the same proportion of the prescribed dose of nebulized fluticasone, beclomethasone dipropionate (BDP) and flunisolide.
Epistatic interaction of genetic depression risk variants in the human subgenual cingulate cortex during memory encoding. - Schott, BH; Assmann, A; Schmierer, P; Soch, J; Erk, S; Garbusow, M; Mohnke, S; Pöhland, L; Romanczuk-Seiferth, N; Barman, A; Wüstenberg, T; Haddad, L; Grimm, O; Witt, S; Richter, S; Klein, M; Schütze, H; Mühleisen, TW; Cichon, S; Rietschel, M; Noethen, MM; Tost, H; Gundelfinger, ED; Düzel, E; Heinz, A; Meyer-Lindenberg, A; Seidenbecher, CI; Walter, H
Recent genome-wide association studies have pointed to single-nucleotide polymorphisms (SNPs) in genes encoding the neuronal calcium channel CaV1.2 (CACNA1C; rs1006737) and the presynaptic active zone protein Piccolo (PCLO; rs2522833) as risk factors for affective disorders, particularly major depression. Previous neuroimaging studies of depression-related endophenotypes have highlighted the role of the subgenual cingulate cortex (CG25) in negative mood and depressive psychopathology. Here, we aimed to assess how recently associated PCLO and CACNA1C depression risk alleles jointly affect memory-related CG25 activity as an intermediate phenotype in clinically healthy humans. To investigate the combined effects of rs1006737 and rs2522833 on the CG25 response,...
Genetic variation of the RASGRF1 regulatory region affects human hippocampus-dependent memory. - Barman, A; Assmann, A; Richter, S; Soch, J; Schütze, H; Wüstenberg, T; Deibele, A; Klein, M; Richter, A; Behnisch, G; Düzel, E; Zenker, M; Seidenbecher, CI; Schott, BH
The guanine nucleotide exchange factor RASGRF1 is an important regulator of intracellular signaling and neural plasticity in the brain. RASGRF1-deficient mice exhibit a complex phenotype with learning deficits and ocular abnormalities. Also in humans, a genome-wide association study has identified the single nucleotide polymorphism (SNP) rs8027411 in the putative transcription regulatory region of RASGRF1 as a risk variant of myopia. Here we aimed to assess whether, in line with the RASGRF1 knockout mouse phenotype, rs8027411 might also be associated with human memory function. We performed computer-based neuropsychological learning experiments in two independent cohorts of young, healthy participants. Tests included the...
Power Transfer Management For Local Power Sources Of A Grid-Tied Load. (2011) - McKinley, AF
A power transfer system provides power factor conditioning of the generated power. Power is received from a local power source, converted to usable AC power, and the power factor is conditioned to a desired value. The desired value may be a power factor at or near unity, or the desired power factor may be in response to conditions of the power grid, a tariff established, and/or determinations made remotely to the local power source. Many sources and power transfer systems can be put together and controlled as a power source farm to deliver power to the grid having a specific...
Adaptive generation and control of arbitrary electrical waveforms in a grid-tied power conversion system - McKinley, AF
A power conversion system converges an output waveform toward a reference waveform representing an ideal version of the desired output waveform. The system receives characteristic information about shape and phase of a target periodic waveform, generates an output waveform, and compares the output waveform to the reference waveform. The comparison can result in correction signals to change the output hardware to change the output waveform to more closely match the reference waveform. The system can converge an output waveform for an ideal voltage or current waveform, and may introduce phase shifting. A power system can output a power signal having...
Valenced action/inhibition learning in humans is modulated by a genetic variant linked to dopamine D2 receptor expression. - Richter, A; Guitart-Masip, M; Barman, A; Libeau, C; Behnisch, G; Czerney, S; Schanze, D; Assmann, A; Klein, M; Düzel, E; Zenker, M; Seidenbecher, CI; Schott, BH
Motivational salience plays an important role in shaping human behavior, but recent studies demonstrate that human performance is not uniformly improved by motivation. Instead, action has been shown to dominate valence in motivated tasks, and it is particularly difficult for humans to learn the inhibition of an action to obtain a reward, but the neural mechanism behind this behavioral specificity is yet unclear. In all mammals, including humans, the monoamine neurotransmitter dopamine is particularly important in the neural manifestation of appetitively motivated behavior, and the human dopamine system is subject to considerable genetic variability. The well-studied TaqIA restriction fragment length...
Vascular hippocampal plasticity after aerobic exercise in older adults. - Maass, A; Düzel, S; Goerke, M; Becke, A; Sobieray, U; Neumann, K; Lövden, M; Lindenberger, U; Bäckman, L; Braun-Dullaeus, R; Ahrens, D; Heinze, HJ; Müller, NG; Düzel, E
Aerobic exercise in young adults can induce vascular plasticity in the hippocampus, a critical region for recall and recognition memory. In a mechanistic proof-of-concept intervention over 3 months, we investigated whether healthy older adults (60-77 years) also show such plasticity. Regional cerebral blood flow (rCBF) and volume (rCBV) were measured with gadolinium-based perfusion imaging (3 Tesla magnetic resonance image (MRI)). Hippocampal volumes were assessed by high-resolution 7 Tesla MRI. Fitness improvement correlated with changes in hippocampal perfusion and hippocampal head volume. Perfusion tended to increase in younger, but to decrease in older individuals. The changes in fitness, hippocampal perfusion and...
Aqueous dual-tailed surfactants simulated on the alumina surface. - Liu, Z; Yu, JG; O'Rear, EA; Striolo, A
Atomistic molecular dynamics (MD) simulations were used to compare the morphology of aqueous surfactant self-assembled aggregates on a flat alumina substrate. The substrate was modeled using the CLAYFF force field, and it was considered fully protonated. Three ionic surfactants were considered, all with a sulfate headgroup. The first surfactant was the single-tailed, widely studied sodium dodecyl sulfate (SDS), for which previous simulation results are available on several substrates. The results obtained for this surfactant were used for benchmarking the behavior of two dual-tailed surfactants. These latter surfactants have equal structure, except that in one case both linear tails are composed...
Preferential adsorption from liquid water-ethanol mixtures in alumina pores. - Phan, A; Cole, DR; Striolo, A
The sorptivity, structure, and dynamics of liquid water-ethanol mixtures confined in alumina pores were studied by molecular dynamics simulations. Due to an effective stronger attraction between water and the alumina surface, our simulations show that water is preferentially adsorbed in alumina nanopores from bulk solutions of varying composition. These results are in good qualitative agreement with experimental data reported by Rao and Sircar (Adsorpt. Sci. Technol. 1993, 10, 93). Analysis of the simulated trajectories allows us to predict that water diffuses through the narrow pores more easily than ethanol, in part because of its smaller size. Our results suggest that...
Self-assembled surfactants on patterned surfaces: confinement and cooperative effects on aggregate morphology. - Suttipong, M; Grady, BP; Striolo, A
The adsorption and self-assembly of surfactants are ubiquitous processes in several technological applications, including the manufacture of nano-structured materials using bottom-up strategies. Although much is known about the adsorption of surfactants on homogeneous flat surfaces from experiments, theory, and simulations, limited information is available, in quantifiable terms, regarding the adsorption of surfactants on surfaces with chemical and/or morphological heterogeneity. In an effort to fill this knowledge gap, we report here results obtained using equilibrium dissipative particle dynamics (DPD) simulations for the adsorption of model surfactants onto patterned flat surfaces (i.e., flat surfaces with chemical heterogeneity). The patterns consist of one...
Competitive surfactant adsorption of AOT and Tween 20 on gold measured using a quartz crystal microbalance with dissipation. - Thavorn, J; Hamon, JJ; Kitiyanan, B; Striolo, A; Grady, BP
Competitive surfactant adsorption of anionic surfactant AOT and nonionic surfactant Tween 20 on gold was investigated by using a quartz crystal microbalance with dissipation (QCM-D) at 25 °C. The adsorption isotherm of pure AOT did not reach a plateau at the CMC, but rather adsorption continued to increase gradually at concentrations higher than the CMC before reaching a plateau. This behavior is evidence of competitive adsorption between AOT and impurities. The adsorbed layer of AOT on gold became more viscoelastic as the concentration of AOT increased. Tween 20 reached the plateau adsorption on gold before its concentration reached the CMC,...
Ellipsoidal Janus nanoparticles adsorbed at the water-oil interface: some evidence of emergent behavior. - Luu, XC; Yu, J; Striolo, A
The equilibrium behavior of ellipsoidal Janus nanoparticles at water-oil interfaces was investigated using dissipative particle dynamics simulations. It was found that the orientation of the nanoparticles with respect to the interface depends on nanoparticle aspect ratio, on the amount of polar vs nonpolar surface groups, and on the interactions between the nanoparticles surface groups and aqueous and nonaqueous solvents. The changes in nanoparticle orientation are not always monotonic, probably because of a competition between different driving forces. For nanoparticles of high aspect ratio, steric effects seem to cause an isotropic-to-nematic phase transition as the surface coverage increases. It was observed...