1,067 research outputs found
Minimally invasive methodology for pharmacological research involving children
This thesis covers a variety of topics around the central theme of pharmacological research involving children, with a specific focus on the development of minimally invasive methodology that can be employed in future studies involving children. Children form a unique group within the area of pharmacological research and pharmacotherapy. The heterogeneity even within this group is large, covering the range of preterm neonates weighing 500 grams up to adolescents. Obviously, therapeutic needs change across this range, as among others disease epidemiology, drug disposition, pharmacodynamic response, and suitable drug formulations change with age. The same holds true for the design of drug trials involving children: where pharmacokinetics in adults can be studied simply by recruiting a number of healthy volunteers, such a study with a number of healthy toddlers is clearly not feasible and not acceptable. Therefore, approaches and new methodology are needed to circumvent these issues.UBL - phd migration 201
Reaming debris as a novel source of autologous bone to enhance healing of bone defects
Item does not contain fulltextReaming debris is formed when bone defects are stabilized with an intramedullary nail, and contains viable osteoblast-like cells and growth factors, and might thus act as a natural osteoinductive scaffold. The advantage of using reaming debris over stem cells or autologous bone for healing bone defects is that no extra surgery is needed to obtain the material. To assess the clinical feasibility of using reaming debris to enhance bone healing, we investigated whether reaming debris enhances the healing rate of a bone defect in sheep tibia, compared to an empty gap. As golden standard the defect was filled with iliac crest bone. Bones treated with iliac crest bone and reaming debris showed larger callus volume, increased bone volume, and decreased cartilage volume in the fracture gap, and increased torsional toughness compared to the empty gap group at 3 weeks postoperative. In addition, bones treated with reaming debris showed increased torsional stiffness at 6 weeks postoperatively compared to the empty defect group, while bending stiffness was marginally increased. These results indicate that reaming debris could serve as an excellent alternative to iliac crest bone for speeding up the healing process in bone defects that are treated with an intramedullary nail
Electrodynamics of quasi-two-dimensional BEDT-TTF charge transfer salts
We consider the millimeter-wave electrodynamics specific to
quasi-two-dimensional conductors and superconductors based on the organic donor
molecule BEDT-TTF. Using realistic physical parameters, we examine the current
polarizations that result for different oscillating (GHz) electric and magnetic
field polarizations. We show that, in general, it is possible to discriminate
between effects (dissipation and dispersion) due to in-plane and interlayer ac
currents. However, we also show that it is not possible to selectively probe
any single component of the in-plane conductivity tensor, and that excitation
of interlayer currents is strongly influenced by the sample geometry and the
electromagnetic field polarization.Comment: 5 pages including 3 figures Minor correction to figure
Transient thermal effects in solid noble gases as materials for the detection of Dark Matter
The transient phenomena produced in solid noble gases by the stopping of the
recoils resulting from the elastic scattering processes of WIMPs from the
galactic halo were modelled, as dependencies of the temperatures of lattice and
electronic subsystems on the distance to the recoil's trajectory, and time from
its passage. The peculiarities of these thermal transients produced in Ar, Kr
and Xe were analysed for different initial temperatures and WIMP energies, and
were correlated with the characteristics of the targets and with the energy
loss of the recoils. The results were compared with the thermal spikes produced
by the same WIMPs in Si and Ge. In the range of the energy of interest, up to
tens of keV for the self-recoil, local phase transitions solid - liquid and
even liquid - gas were found possible, and the threshold parameters were
established.Comment: Minor corrections and updated references; accepted to JCA
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Threats to the validity of the Collegiate Learning Assessment (CLA+) as a measure of critical thinking skills and implications for Learning Gain
The University of Reading Learning Gain project is a three-year longitudinal project to test and evaluate a range of available methodologies and to draw conclusions on what might be the right combination of instruments for the measurement of Learning Gain in higher education. This paper analyses the validity of a measure of critical thinking skills, the Collegiate Learning Assessment (CLA+) and the implications of using this standardised test as a proxy for Learning Gain. The paper reviews five inferences regarding the interpretations and use of test scores: construct representation, scoring, generalisation, extrapolation and decision-making. Each section reviews some of the available evidence in support of the claims the CLA+ makes and the threats to their validity. The possible impact of these issues on Learning Gain in the UK is considered
ESC NN-Potentials in Momentum Space. I. PS-PS Exchange Potentials
A momentum space representation is derived for the Nijmegen
Extended-Soft-Core (ESC) interactions. The partial wave projection of this
representation is carried through, in principle for Two-Meson-Exchange (TME) in
general. Explicit results for the momentum space partial wave NN-potentials
from PS-PS-Exchange are given.Comment: 23 pages, 2 PostScript figures, revtex
Cluster Monte Carlo study of multi-component fluids of the Stillinger-Helfand and Widom-Rowlinson type
Phase transitions of fluid mixtures of the type introduced by Stillinger and
Helfand are studied using a continuum version of the invaded cluster algorithm.
Particles of the same species do not interact, but particles of different types
interact with each other via a repulsive potential. Examples of interactions
include the Gaussian molecule potential and a repulsive step potential.
Accurate values of the critical density, fugacity and magnetic exponent are
found in two and three dimensions for the two-species model. The effect of
varying the number of species and of introducing quenched impurities is also
investigated. In all the cases studied, mixtures of -species are found to
have properties similar to -state Potts models.Comment: 25 pages, 5 figure
Relativistic effects and quasipotential equations
We compare the scattering amplitude resulting from the several quasipotential
equations for scalar particles. We consider the Blankenbecler-Sugar, Spectator,
Thompson, Erkelenz-Holinde and Equal-Time equations, which were solved
numerically without decomposition into partial waves. We analyze both
negative-energy state components of the propagators and retardation effects. We
found that the scattering solutions of the Spectator and the Equal-Time
equations are very close to the nonrelativistic solution even at high energies.
The overall relativistic effect increases with the energy. The width of the
band for the relative uncertainty in the real part of the scattering
matrix, due to different dynamical equations, is largest for
backward-scattering angles where it can be as large as 40%.Comment: Accepted for publication in Phys. Rev.
FRW Cosmology From Five Dimensional Vacuum Brans-Dicke Theory
We follow approach of induced matter theory for 5D vacuum BD, introduce
induced matter and potential in 4D hypersurfaces, and employ generalized FRW
type solution. We confine ourselves to scalar field and scale factors be
functions of the time. This makes the induced potential, by its definition,
vanishes. When the scale factor of fifth dimension and scalar field are not
constants, 5D eqs for any geometry admit a power law relation between scalar
field and scale factor of fifth dimension. Hence the procedure exhibits that 5D
vacuum FRW like eqs are equivalent, in general, to corresponding 4D vacuum ones
with the same spatial scale factor but new scalar field and coupling constant.
We show that 5D vacuum FRW like eqs or its equivalent 4D vacuum ones admit
accelerated solutions. For constant scalar field, eqs reduce to usual FRW eqs
with typical radiation dominated universe. For this situation we obtain
dynamics of scale factors for any geometry without any priori assumption. For
nonconstant scalar fields and spatially flat geometries, solutions are found to
be power law and exponential ones. We also employ weak energy condition for
induced matter, that allows negative/positive pressures. All types of solutions
fulfill WEC in different ranges. The power law solutions with negative/positive
pressures admit both decelerating and accelerating ones. Some solutions accept
shrinking extra dimension. By considering nonghost scalar fields and recent
observational measurements, solutions are more restricted. We illustrate that
accelerating power law solutions, which satisfy WEC and have nonghost fields,
are compatible with recent observations in ranges -4/3 < \omega </- -1.3151 and
1.5208 </- n < 1.9583 for dependence of fifth dimension scale factor with usual
scale factor. These ranges also fulfill condition nonghost fields in the
equivalent 4D vacuum BD eqs.Comment: 18 pages, 16 figures, 11 table
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