27,483 research outputs found
Cell Therapy for Type 1 Diabetes
Acknowledgements The work described in this review was supported by a grant from the MRC. K.R.M. is supported by a fellowship from the Scottish Translational Medicines and Therapeutics Initiative through the Wellcome Trust.Peer reviewedPublisher PD
An accurate formula for the period of a simple pendulum oscillating beyond the small-angle regime
A simple approximation formula is derived here for the dependence of the
period of a simple pendulum on amplitude that only requires a pocket calculator
and furnishes an error of less than 0.25% with respect to the exact period. It
is shown that this formula describes the increase of the pendulum period with
amplitude better than other simple formulas found in literature. A good
agreement with experimental data for a low air-resistance pendulum is also
verified and it suggests, together with the current availability/precision of
timers and detectors, that the proposed formula is useful for extending the
pendulum experiment beyond the usual small-angle oscillations.Comment: 15 pages and 4 figures. to appear in American Journal of Physic
Axisymmetric polydimethysiloxane microchannels for in vitro hemodynamic studies
The current microdevices used for biomedical research are often manufactured using microelectromechanical systems (MEMS) technology. Although it is possible to fabricate precise and reproducible rectangular microchannels using soft lithography techniques, this kind of geometry may not reflect the actual physiology of the microcirculation. Here, we present a simple method to fabricate circular polydimethysiloxane (PDMS) microchannels aiming to mimic an in vivo microvascular environment and suitable for state-of-the-art microscale flow visualization techniques, such as confocal µPIV/PTV. By using a confocal µPTV system individual red blood cells (RBCs) were successfully tracked trough a 75 µm circular PDMS microchannel. The results show that RBC lateral dispersion increases with the volume fraction of RBCs in the solution, i.e. with the hematocrit
Comparison of Ising magnet on directed versus undirected Erdos-Renyi and scale-free network
Scale-free networks are a recently developed approach to model the
interactions found in complex natural and man-made systems. Such networks
exhibit a power-law distribution of node link (degree) frequencies n(k) in
which a small number of highly connected nodes predominate over a much greater
number of sparsely connected ones. In contrast, in an Erdos-Renyi network each
of N sites is connected to every site with a low probability p (of the orde r
of 1/N). Then the number k of neighbors will fluctuate according to a Poisson
distribution. One can instead assume that each site selects exactly k neighbors
among the other sites. Here we compare in both cases the usual network with the
directed network, when site A selects site B as a neighbor, and then B
influences A but A does not influence B. As we change from undirected to
directed scale-free networks, the spontaneous magnetization vanishes after an
equilibration time following an Arrhenius law, while the directed ER networks
have a positive Curie temperature.Comment: 10 pages including all figures, for Int. J, Mod. Phys. C 1
Critical wave-packet dynamics in the power-law bond disordered Anderson Model
We investigate the wave-packet dynamics of the power-law bond disordered
one-dimensional Anderson model with hopping amplitudes decreasing as
. We consider the critical case ().
Using an exact diagonalization scheme on finite chains, we compute the
participation moments of all stationary energy eigenstates as well as the
spreading of an initially localized wave-packet. The eigenstates
multifractality is characterized by the set of fractal dimensions of the
participation moments. The wave-packet shows a diffusive-like spread developing
a power-law tail and achieves a stationary non-uniform profile after reflecting
at the chain boundaries. As a consequence, the time-dependent participation
moments exhibit two distinct scaling regimes. We formulate a finite-size
scaling hypothesis for the participation moments relating their scaling
exponents to the ones governing the return probability and wave-function
power-law decays
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