373 research outputs found
Optimal or antagonistic? muscle force solutions in the lower limb
Provides evidence of the appropriateness of different muscle force distribution protocols in a musculoskeletal model of the lower limb
Magnetic breakdown in a normal-metal - superconductor proximity sandwich
We study the magnetic response of a clean normal-metal slab of finite
thickness in proximity with a bulk superconductor. We determine its free energy
and identify two (meta-)stable states, a diamagnetic one where the applied
field is effectively screened, and a second state, where the field penetrates
the normal-metal layer. We present a complete characterization of the first
order transition between the two states which occurs at the breakdown field,
including its spinodals, the jump in the magnetization, and the latent heat.
The bistable regime terminates at a critical temperature above which the sharp
transition is replaced by a continuous cross-over. We compare the theory with
experiments on normal-superconducting cylinders.Comment: 7 pages Revtex, 3 Postscript figures, needs psfig.te
Gemini Observations of Disks and Jets in Young Stellar Objects and in Active Galaxies
We present first results from the Near-infrared Integral Field Spectrograph
(NIFS) located at Gemini North. For the active galaxies Cygnus A and Perseus A
we observe rotationally-supported accretion disks and adduce the existence of
massive central black holes and estimate their masses. In Cygnus A we also see
remarkable high-excitation ionization cones dominated by photoionization from
the central engine. In the T-Tauri stars HV Tau C and DG Tau we see
highly-collimated bipolar outflows in the [Fe II] 1.644 micron line, surrounded
by a slower molecular bipolar outflow seen in the H_2 lines, in accordance with
the model advocated by Pyo et al. (2002).Comment: Invited paper presented at the 5th Stromlo Symposium. 9 pages, 7
figures. Accepted for publication in Astrophysics & Space Scienc
Overscreening Diamagnetism in Cylindrical Superconductor-Normal Metal-Heterostructures
We study the linear diamagnetic response of a superconducting cylinder coated
by a normal-metal layer due to the proximity effect using the clean limit
quasiclassical Eilenberger equations. We compare the results for the
susceptibility with those for a planar geometry. Interestingly, for
the cylinder exhibits a stronger overscreening of the magnetic field, i.e., at
the interface to the superconductor it can be less than (-1/2) of the applied
field. Even for , the diamagnetism can be increased as compared to the
planar case, viz. the magnetic susceptibility becomes smaller than
-3/4. This behaviour can be explained by an intriguing spatial oscillation of
the magnetic field in the normal layer
Cavity QED and quantum information processing with "hot" trapped atoms
We propose a method to implement cavity QED and quantum information
processing in high-Q cavities with a single trapped but non-localized atom. The
system is beyond the Lamb-Dick limit due to the atomic thermal motion. Our
method is based on adiabatic passages, which make the relevant dynamics
insensitive to the randomness of the atom position with an appropriate
interaction configuration. The validity of this method is demonstrated from
both approximate analytical calculations and exact numerical simulations. We
also discuss various applications of this method based on the current
experimental technology.Comment: 14 pages, 8 figures, Revte
cis-Acting Complex-Trait-Associated lincRNA Expression Correlates with Modulation of Chromosomal Architecture.
Intergenic long noncoding RNAs (lincRNAs) are the largest class of transcripts in the human genome. Although many have recently been linked to complex human traits, the underlying mechanisms for most of these transcripts remain undetermined. We investigated the regulatory roles of a high-confidence and reproducible set of 69 trait-relevant lincRNAs (TR-lincRNAs) in human lymphoblastoid cells whose biological relevance is supported by their evolutionary conservation during recent human history and genetic interactions with other trait-associated loci. Their enrichment in enhancer-like chromatin signatures, interactions with nearby trait-relevant protein-coding loci, and preferential location at topologically associated domain (TAD) boundaries provide evidence that TR-lincRNAs likely regulate proximal trait-relevant gene expression in cis by modulating local chromosomal architecture. This is consistent with the positive and significant correlation found between TR-lincRNA abundance and intra-TAD DNA-DNA contacts. Our results provide insights into the molecular mode of action by which TR-lincRNAs contribute to complex human traits
Population pharmacokinetics of clonazepam in saliva and plasma: steps towards noninvasive pharmacokinetic studies in vulnerable populations
Aim Traditional studies focusing on the relationship between pharmacokinetics (PK) and pharmacodynamics necessitate blood draws, which are too invasive for children or other vulnerable populations. A potential solution is to use noninvasive sampling matrices, such as saliva. The aim of this study was to develop a population PK model describing the relationship between plasma and saliva clonazepam kinetics and assess whether the model can be used to determine trough plasma concentrations based on saliva samples. Methods Twenty healthy subjects, aged 18-30, were recruited and administered 0.5 or 1 mg of clonazepam solution. Paired plasma and saliva samples were obtained until 48 hours post-dose. A population pharmacokinetic model was developed describing the PK of clonazepam in plasma and the relationship between plasma and saliva concentrations. Bayesian maximum a posteriori optimization was applied to estimate the predictive accuracy of the model. Results A two-compartment distribution model best characterized clonazepam plasma kinetics with a mixture component on the absorption rate constants. Oral administration of the clonazepam solution caused contamination of the saliva compartment during the first 4 hours post-dose, after which the concentrations were driven by the plasma concentrations. Simulations demonstrated that the lower and upper limits of agreements between true and predicted plasma concentrations were -28% to 36% with one saliva sample. Increasing the number of saliva samples improved these limits to -18% to 17%. Conclusion The developed model described the salivary and plasma kinetics of clonazepam, and could predict steady-state trough plasma concentrations based on saliva concentrations with acceptable accuracy.Genetics of disease, diagnosis and treatmen
Fast Approximated POD for a Flat Plate Benchmark with a Time Varying Angle of Attack
An approximate POD algorithm provides an empirical Galerkin approximation with guaranteed a priori lower bound on the required resolution. The snapshot ensemble is partitioned into several sub-ensembles. Cross correlations between these sub-ensembles are approximated in terms of a far smaller correlation matrix. Computational speedup is nearly linear in the number of partitions, up to a saturation that can be estimated a priori. The algorithm is particularly suitable for analyzing long transient trajectories of high dimensional simulations, but can be applied also for spatial partitioning and parallel processing of very high spatial dimension data. The algorithm is demonstrated using transient data from two simulations. First, a two dimensional simulation of the flow over a flat plate, as it transitions from AOA = 30° to a horizontal position and back. Second, a three dimensional simulation of a flat plate with aspect ratio two as it transitions from a horizontal position to AOA = 30°
- …