8,267 research outputs found
Development of the cancer-related loneliness assessment tool:Using the findings of a qualitative analysis to generate questionnaire items
The aim of this research was to develop a tool to identify and assess the qualities of cancer-related loneliness in adult cancer survivors who have completed treatment. In addition to reporting the development of the tool, we explicate the process of using the findings of a qualitative analysis to generate questionnaire items, as currently little guidance exists on this topic. The findings of our qualitative research exploring the experience of loneliness in adult cancer survivors who had completed treatment, together with the findings of our concept analysis of loneliness, were used to develop an assessment tool for cancer-related loneliness following treatment completion. Cognitive testing was undertaken to assess fidelity of comprehension and feasibility in administration. The Cancer-Related Loneliness Assessment Tool is a 10-item self-report questionnaire capturing the essential elements of cancer-related loneliness following treatment completion. Experts believed the questionnaire to be face-valid and usable in clinical practice, and preliminary cognitive testing indicated that the items generate the information intended and individuals have little trouble completing the tool. Following further development work, the tool could be employed to identify cancer-related loneliness following treatment completion. It could also aid with the development/adaptation and evaluation of person-centred interventions to address such loneliness.</p
Quenched charge disorder in CuO2 spin chains: Experimental and numerical studies
We report on measurements of the magnetic response of the anisotropic CuO_2
spin chains in lightly hole-doped La_x (Ca,Sr)_14-x Cu_24 O_41, x>=5. The
experimental data suggest that in magnetic fields B >~ 4T (applied along the
easy axis) the system is characterized by short-range spin order and
quasi-static (quenched) charge disorder. The magnetic susceptibility chi(B)
shows a broad anomaly, which we interpret as the remnant of a spin-flop
transition. To corroborate this idea, we present Monte Carlo simulations of a
classical, anisotropic Heisenberg model with randomly distributed, static
holes. Our numerical results clearly show that the spin-flop transition of the
pure model (without holes) is destroyed and smeared out due to the disorder
introduced by the quasi-static holes. Both the numerically calculated
susceptibility curves chi(B) and the temperature dependence of the position of
the anomaly are in qualitative agreement with the experimental data.Comment: 10 pages, REVTeX4. 11 figures; v2: Fig.2 replaced, small changes in
Figs.1 and 11; minor revisons in Sec. III.C; accepted by Phys. Rev.
Geminin deficiency enhances survival in a murine medulloblastoma model by inducing apoptosis of preneoplastic granule neuron precursors
Dynamic correlations in stochastic rotation dynamics
The dynamic structure factor, vorticity and entropy density dynamic
correlation functions are measured for Stochastic Rotation Dynamics (SRD), a
particle based algorithm for fluctuating fluids. This allows us to obtain
unbiased values for the longitudinal transport coefficients such as thermal
diffusivity and bulk viscosity. The results are in good agreement with earlier
numerical and theoretical results, and it is shown for the first time that the
bulk viscosity is indeed zero for this algorithm. In addition, corrections to
the self-diffusion coefficient and shear viscosity arising from the breakdown
of the molecular chaos approximation at small mean free paths are analyzed. In
addition to deriving the form of the leading correlation corrections to these
transport coefficients, the probabilities that two and three particles remain
collision partners for consecutive time steps are derived analytically in the
limit of small mean free path. The results of this paper verify that we have an
excellent understanding of the SRD algorithm at the kinetic level and that
analytic expressions for the transport coefficients derived elsewhere do indeed
provide a very accurate description of the SRD fluid.Comment: 33 pages including 16 figure
Kink-induced transport and segregation in oscillated granular layers
We use experiments and molecular dynamics simulations of vertically
oscillated granular layers to study horizontal particle segregation induced by
a kink (a boundary between domains oscillating out of phase). Counter-rotating
convection rolls carry the larger particles in a bidisperse layer along the
granular surface to a kink, where they become trapped. The convection
originates from avalanches that occur inside the layer, along the interface
between solidified and fluidized grains. The position of a kink can be
controlled by modulation of the container frequency, making possible systematic
harvesting of the larger particles.Comment: 4 pages, 5 figures. to appear in Phys. Rev. Let
Infinite Momentum Frame Calculation of Semileptonic Heavy \Lambda_b\to\Lambda_c Transitions Including HQET Improvements
We calculate the transition form factors that occur in heavy -type
baryon semileptonic decays as e.g. in . We use Bauer-Stech-Wirbel type infinite momentum frame wave
functions for the heavy -type baryons which we assume to consist of a
heavy quark and a light spin-isospin zero diquark system. The form factors at are calculated from the overlap integrals of the initial and final
-type baryon states. To leading order in the heavy mass scale the
structure of the form factors agrees with the HQET predictions including the
normalization at zero recoil. The leading order -dependence of the form
factors is extracted by scaling arguments. By comparing the model form factors
with the HQET predictions at we obtain a consistent set of
model form factors up to . With our preferred choice of
parameter values we find that the contribution of the non-leading form factor
is practically negligible. We use our form factor predictions to compute rates,
spectra and various asymmetry parameters for the semi-leptonic decay
.Comment: 24 pages, LaTeX, 6 figures are included in PostScript format. Final
version of paper to appear in Phys.Rev.
Exclusive hadronization in gamma* gamma -> pi pi
We perform a QCD analysis of exclusive two-meson production in gamma* gamma
collisions in the kinematical domain of large photon virtuality Q^2 and small
hadronic invariant mass W^2. In these kinematics the amplitude factorizes into
a perturbative subprocess gamma* gamma -> q qbar and a two-meson distribution
amplitude. This opens the way to study new hadronic matrix elements related
with the physics of hadronization and confinement.Comment: 5 pages, 1 figure. Talk given at PHOTON 99, Freiburg, Germany, 23-27
May 1999. Eq. (8) correcte
X-ray absorption spectroscopy on layered cobaltates Na_xCoO_2
Measurements of polarization and temperature dependent soft x-ray absorption
have been performed on Na_xCoO_2 single crystals with x=0.4 and x=0.6. They
show a deviation of the local trigonal symmetry of the CoO_6 octahedra, which
is temperature independent in a temperature range between 25 K and 372 K. This
deviation was found to be different for Co^{3+} and Co^{4+} sites. With the
help of a cluster calculation we are able to interpret the Co L_{23}-edge
absorption spectrum and find a doping dependent energy splitting between the
t_{2g} and the e_g levels (10Dq) in Na_xCoO_2.Comment: 7 pages, 8 figure
A computational model of the hypothalamic - pituitary - gonadal axis in female fathead minnows (Pimephales promelas) exposed to 17α-ethynylestradiol and 17β-trenbolone
© 2011 Li et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.Background - Endocrine disrupting chemicals (e.g., estrogens, androgens and their mimics) are known to affect reproduction in fish. 17α-ethynylestradiol is a synthetic estrogen used in birth control pills. 17β-trenbolone is a relatively stable metabolite of trenbolone acetate, a synthetic androgen used as a growth promoter in livestock. Both 17α-ethynylestradiol and 17β-trenbolone have been found in the aquatic environment and affect fish reproduction. In this study, we developed a physiologically-based computational model for female fathead minnows (FHM, Pimephales promelas), a small fish species used in ecotoxicology, to simulate how estrogens (i.e., 17α-ethynylestradiol) or androgens (i.e., 17β-trenbolone) affect reproductive endpoints such as plasma concentrations of steroid hormones (e.g., 17β-estradiol and testosterone) and vitellogenin (a precursor to egg yolk proteins).
Results - Using Markov Chain Monte Carlo simulations, the model was calibrated with data from unexposed, 17α-ethynylestradiol-exposed, and 17β-trenbolone-exposed FHMs. Four Markov chains were simulated, and the chains for each calibrated model parameter (26 in total) converged within 20,000 iterations. With the converged parameter values, we evaluated the model's predictive ability by simulating a variety of independent experimental data. The model predictions agreed with the experimental data well.
Conclusions - The physiologically-based computational model represents the hypothalamic-pituitary-gonadal axis in adult female FHM robustly. The model is useful to estimate how estrogens (e.g., 17α-ethynylestradiol) or androgens (e.g., 17β-trenbolone) affect plasma concentrations of 17β-estradiol, testosterone and vitellogenin, which are important determinants of fecundity in fish.The Medical Research Foundation of Oregon, U.S. Environmental Protection
Agency, and the National Center for Computational Toxicology of the EPA Office of
Research and Development
Exclusive Photoproduction of Large Momentum-Transfer K and K* Mesons
The reactions gamma p -> K+ Lambda and gamma p -> K* Lambda are analyzed
within perturbative QCD, allowing for diquarks as quasi-elementary constituents
of baryons. The diquark-model parameters and the quark-diquark distribution
amplitudes of proton and Lambda are taken from previous investigations of
electromagnetic baryon form factors and Compton-scattering off protons.
Unpolarized differential cross sections and polarization observables are
computed for different choices of the K and K* distribution amplitudes. The
asymptotic form of the K distribution amplitude (proportional to x1 x2) is
found to provide a satisfactory description of the K photoproduction data.Comment: 32 pages, 7 figures available as tared, compressed and uuencoded
PS-file
- …