Effect of an electric field on a floating lipid bilayer: a neutron reflectivity study

We present here a neutron reflectivity study of the influence of an alternative electric field on a supported phospholipid double bilayer. We report for the first time a reproducible increase of the fluctuation amplitude leading to the complete unbinding of the floating bilayer. Results are in good agreement with a semi-quantitative interpretation in terms of negative electrostatic surface tension.Comment: 12 pages, 7 figures, 1 table accepted for publication in European Physical Journal E Replaced with with correct bibliograph

Simple Applications of q-Bosons

A deformation of the harmonic oscillator algebra associated with the Morse potential and the SU(2) algebra is derived using the quantum analogue of the anharmonic oscillator. We use the quantum oscillator algebra or $q$-boson algebra which is a generalisation of the Heisenberg-Weyl algebra obtained by introducing a deformation parameter $q$. Further, we present a new algebraic realization of the $q$-bosons, for the case of $q$ being a root of unity, which corresponds to a periodic structure described by a finite-dimensional representation. We show that this structure represents the symmetry of a linear lattice with periodic boundary conditions.Comment: LATEX2e, 10 pages, v2: few misprints corrected, added Journal-re

Oscillatory Solutions of Neutral Equations with Polynomial Nonlinearities

Existence uniqueness of an oscillatory solution for nonlinear neutral equations by fixed point method is proved

Leadership in a Public Goods Experiment with Permanent and Temporary Members

We experimentally analyze leading by example in a public goods game with two permanent and two temporary group members. Our results show that leadership when permanent and temporary members interact leads to lower contributions than interaction without leadership

Global Stability and Periodicity in a Glucose-Insulin Regulation Model with a Single Delay

A two-dimensional system of differential equations with delay modelling the glucose-insulin interaction processes in the human body is considered. Sufficient conditions are derived for the unique positive equilibrium in the system to be globally asymptotically stable. They are given in terms of the global attractivity of the fixed point in a limiting interval map. The existence of slowly oscillating periodic solutions is shown in the case when the equilibrium is unstable. The mathematical results are supported by extensive numerical simulations. It is shown that typical behaviour in the system is the convergence to either a stable periodic solution or to the unique stable equilibrium. The coexistence of several periodic solutions together with the stable equilibrium is demonstrated as a possibility.Comment: Accepted to Communications in Nonlinear Science and Numerical Simulatio

The hydrocarbon biodegradation potential of Faroe-Shetland Channel bacterioplankton

The Faroe-Shetland Channel (FSC) is an important gateway for dynamic water exchange between the North Atlantic Ocean and the Nordic Seas. In recent years it has also become a frontier for deep-water oil exploration and petroleum production, which has raised the risk of oil pollution to local ecosystems and adjacent waterways. In order to better understand the factors that influence the biodegradation of spilled petroleum, a prerequisite has been recognized to elucidate the complex dynamics of microbial communities and their relationships to their ecosystem. This research project was a pioneering attempt to investigate the FSC’s microbial community composition, its response and potential to degrade crude oil hydrocarbons under the prevailing regional temperature conditions. Three strategies were used to investigate this. Firstly, high throughput sequencing and 16S rRNA gene-based community profiling techniques were utilized to explore the spatiotemporal patterns of the FSC bacterioplankton. Monitoring proceeded over a period of 2 years and interrogated the multiple water masses flowing through the region producing 2 contrasting water cores: Atlantic (surface) and Nordic (subsurface). Results revealed microbial profiles more distinguishable based on water cores (rather than individual water masses) and seasonal variability patterns within each core. Secondly, the response of the microbial communities to crude oil was investigated in laboratory-based microcosms. Microbial communities from all water masses exhibited hydrocarbon biodegradation activity at average FSC temperatures (4°C), albeit with markedly delayed and potentially slower response in comparison to those exposed to moderate control temperatures (20°C). A collection of bacterial isolates, comprising of 230 FSC strains with putative hydrocarbonoclastic activity was created, which included psychrotolerant members belonging to the genera Marinobacter, Pseudoalteromonas, Cycloclasticus, Halomonas, Thalassolituus and Glaciecola. Lastly, a sophisticated molecular technique called DNA-based stable isotope probing (DNA-SIP) was used to directly target and identify hydrocarbon-degrading taxa that may not be easily amenable to cultivation. Using DNA-SIP, hydrocarbonoclastic FSC strains affiliated with the genera Phaeobacter and Lentibacter were identified, along with strains affiliated with known hydrocarbon-degraders from the genera Thalassolituus, Alcanivorax, Oleispira, Glaciecola, Marinobacter and Cycloclasticus. Correlating the findings from all three experiments, revealed that ~41% of the baseline FSC microbial community constituted bacteria affiliated to genera with hydrocarbon-degrading capacities. Their response to the presence of hydrocarbons, however, appeared to be largely influenced by temperature. This work is the first to establish a microbial baseline for the FSC and to investigate the microbial repose to crude oil in the water column of the region. Results are expected to contribute to the development of biotechnologies and oil-spill mitigation strategies tailored for the FSC region in the event of an oil spill

The Application of Constraint Rules to Data-driven Parsing

In this paper, we show an approach to extracting different types of constraint rules from a dependency treebank. Also, we show an approach to integrating these constraint rules into a dependency data-driven parser, where these constraint rules inform parsing decisions in specific situations where a set of parsing rule (which is induced from a classifier) may recommend several recommendations to the parser. Our experiments have shown that parsing accuracy could be improved by using different sets of constraint rules in combination with a set of parsing rules. Our parser is based on the arc-standard algorithm of MaltParser but with a number of extensions, which we will discuss in some detail

Componentes biológicamente activos y beneficios para la salud del aceite de semilla de ortiga

The biologically active components of nettle seed oil and important lipid indices, which are criteria for the health benefits of the oil, have been examined. Linoleic acid predominates in triacylglycerols (77.7%), followed by oleic (16.2%). Sterols in the lipids are present at 1.1% and β-sitosterol is the main component (90.1%). The oil contains 711 mg/kg tocopherols and γ-tocopherol predominates (36.1%), followed by α-tocopherol (28.9%) and δ-tocopherol (26.9%). Atherogenicity and thrombogenicity index values are significantly low, which determine the best anti-atherogenic and anti-thrombogenic properties of the oil. The cholesterolemic index and the ratio of polyunsaturated and saturated fatty acids are considerably higher than 1.0 and reveal good hypocholesterolemic potential and nutritional value. The content of biologically active components of nettle seed oil indicates that it is a rich source of essential fatty acids, sterols and tocopherols and this oil can be used in food, cosmetics, and pharmaceutical products.Se han determinado los componentes biológicamente activos del aceite de semilla de ortiga y los índices lipídicos más importantes, como criterios sobre los beneficios para la salud del aceite. El ácido linoleico predomina en los triacilgliceroles (77,7%), seguido por oleico (16,2%). Los esteroles son el 1,1% siendo el β-sitosterol el componente mayoritario (90,1%). Los tocoferoles son 711 mg/kg y predomina el γ-tocoferol (36,1%), seguido por α-tocoferol (28,9%) y δ-tocoferol (26,9%). Los valores de los índices de aterogenicidad y trombogenicidad son significativamente bajos, lo que determina las buenas propiedades antiaterogénicas y antitrombogénicas del aceite. El índice hipo/hipercolesterolémico y la proporción de ácidos grasos poliinsaturados y saturados presentan valores altos (superiores a 1,0), lo cual indica un buen potencial hipocolesterolémico y valor nutricional del aceite. El contenido de componentes biológicamente activos del aceite de semilla de ortiga muestra que es un producto rico de ácidos grasos esenciales, esteroles y tocoferoles, y por eso se puede utilizar en alimentos, cosméticos y productos farmacéuticos

Inter- and intra-annual bacterioplankton community patterns in a deepwater sub-Arctic region:Persistent high background abundance of putative oil degraders

Oil spills at sea are one of the most disastrous anthropogenic pollution events, with the Deepwater Horizon spill providing a testament to how profoundly the health of marine ecosystems and the livelihood of its coastal inhabitants can be severely impacted by spilled oil. The fate of oil in the environment is largely dictated by the presence and activities of natural communities of oil-degrading bacteria