921 research outputs found
The effect of trapping superparamagnetic beads on domain wall motion
Domain walls may act as localized field sources to trap and move superparamagnetic beads for manipulating biological cells and DNA. The interaction between beads of various diameters and a wall is investigated using a combination of micromagnetic and analytical models. Domain walls can transport beads under applied magnetic fields but the mutual attraction between the bead and wall causes drag forces affecting the bead to couple into the wall motion. Therefore, the interaction with the bead causes a fundamental change in the domain wall dynamics, reducing the wall mobility by five orders of magnitude. (C) 2010 American Institute of Physics. [doi:10.1063/1.3428775
Case study analysis of end of life care development in the Chinese cultural context of Macao:A social movement perspective
Abstract Background The modern hospice movement is often recognised as a social movement. However, such understanding is primarily based on historic reflection and this approach has lacked theoretical exploration. There is a lack of systematic examination of the modern hospice movement by way of social movement theories. Aim Focusing on the Chinese socio-cultural context of Macao, this study aimed to understand the EoLC movement by applying the social movement theory, the Framing Perspective, as proposed by Snow and Benford in 1988. Methods A case study approach was conducted. Semi-structured interviews were held between 2012 and 2013, with pioneers (nâ=â11) of the EoLC in Macao. Thematic analysis was adopted to analyse the interviews. Results The Framing Perspective analysis illuminated that there was both growth and stagnation of the EoLC movement. Three themes emerged: 1) the suffering of people at the end of their lives was considered as a social problem needed to be addressed urgently, 2) the incoherent EoLC strategies developed by pioneers indicated the lack of internal ideological cohesion within the movement, 3) external constraints contributed to the stagnation of the movement. Conclusions The EoLC development in Macao can be understood as a social movement. The Framing Perspective provided a theoretical way to understand the emergence of EoLC; offering a novel perspective to conceptualise the modern hospice movement. This sociological and theoretical lens opened up new ways for future research to study the emergence of EoLC in different socio-cultural contexts
Measuring the Quantum State of a Large Angular Momentum
We demonstrate a general method to measure the quantum state of an angular
momentum of arbitrary magnitude. The (2F+1) x (2F+1) density matrix is
completely determined from a set of Stern-Gerlach measurements with (4F+1)
different orientations of the quantization axis. We implement the protocol for
laser cooled Cesium atoms in the 6S_{1/2}(F=4) hyperfine ground state and apply
it to a variety of test states prepared by optical pumping and Larmor
precession. A comparison of input and measured states shows typical
reconstruction fidelities of about 0.95.Comment: 4 pages, 6 figures, submitted to PR
Resolved-sideband Raman cooling to the ground state of an optical lattice
We trap neutral Cs atoms in a two-dimensional optical lattice and cool them
close to the zero-point of motion by resolved-sideband Raman cooling. Sideband
cooling occurs via transitions between the vibrational manifolds associated
with a pair of magnetic sublevels and the required Raman coupling is provided
by the lattice potential itself. We obtain mean vibrational excitations
\bar{n}_x \approx \bar{n}_y \approx 0.01, corresponding to a population \sim
98% in the vibrational ground state. Atoms in the ground state of an optical
lattice provide a new system in which to explore quantum state control and
subrecoil laser coolingComment: PDF file, 13 pages including 3 figure
Long-term increases in neurotransmitter release from neuronal cells expressing a constitutively active adenylate cyclase from a herpes simplex virus type 1 vector.
Nonlinear parametric instability in double-well lattices
A possibility of a nonlinear resonant instability of uniform oscillations in
dynamical lattices with harmonic intersite coupling and onsite nonlinearity is
predicted. Numerical simulations of a lattice with a double-well onsite
anharmonic potential confirm the existence of the nonlinear instability with an
anomalous value of the corresponding power index, 1.57, which is intermediate
between the values 1 and 2 characterizing the linear and nonlinear (quadratic)
instabilities. The anomalous power index may be a result of competition between
the resonant quadratic instability and nonresonant linear instabilities. The
observed instability triggers transition of the lattice into a chaotic
dynamical state.Comment: A latex text file and three pdf files with figures. Physical Review
E, in pres
A tuneable, photocurable, poly(caprolactone)-based resin for tissue engineeringâsynthesis, characterisation and use in stereolithography
Stereolithography is a useful additive manufacturing technique for the production of scaffolds for tissue engineering. Here we present a tuneable, easy-to-manufacture, photocurable resin for use in stereolithography, based on the widely used biomaterial, poly(caprolactone) (PCL). PCL triol was methacrylated to varying degrees and mixed with photoinitiator to produce a photocurable prepolymer resin, which cured under UV light to produce a cytocompatible material. This study demonstrates that poly(caprolactone) methacrylate (PCLMA) can be produced with a range of mechanical properties and degradation rates. By increasing the degree of methacrylation (DM) of the prepolymer, the Youngâs modulus of the crosslinked PCLMA could be varied from 0.12â3.51 MPa. The accelerated degradation rate was also reduced from complete degradation in 17 days to non-significant degradation in 21 days. The additive manufacturing capabilities of the resin were demonstrated by the production of a variety of different 3D structures using micro-stereolithography. Here, ÎČ-carotene was used as a novel, cytocompatible photoabsorber and enabled the production of complex geometries by giving control over cure depth. The PCLMA presented here offers an attractive, tuneable biomaterial for the production of tissue engineering scaffolds for a wide range of applications
Phase Control of Nonadiabaticity-induced Quantum Chaos in An Optical Lattice
The qualitative nature (i.e. integrable vs. chaotic) of the translational
dynamics of a three-level atom in an optical lattice is shown to be
controllable by varying the relative laser phase of two standing wave lasers.
Control is explained in terms of the nonadiabatic transition between optical
potentials and the corresponding regular to chaotic transition in mixed
classical-quantum dynamics. The results are of interest to both areas of
coherent control and quantum chaos.Comment: 3 figures, 4 pages, to appear in Physical Review Letter
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