429 research outputs found
The masses of the mesons and baryons. Part II. The Standing Wave Model
In order to explain the empirical integer multiple rule for the stable mesons
and baryons presented in the preceding paper we assume that the particles are
held together in a cubic nuclear lattice. This is a novel approach to the
particles, based on the fact that the range of the weak nuclear force is only a
thousandth of the diameter of the nucleon, and that the crystals are the
best-known macroscopic bodies held together by a microscopic force. We
investigate the standing waves in a cubic nuclear lattice. From the frequency
distribution of the waves follows that the masses of the -branch
particles are integer multiples of . We show that each particle has
automatically an antiparticle. Assuming that the energy of the oscillations is
determined by Planck's formula for the energy of a linear oscillator, it turns
out that the meson and the other members of the -branch are
like cubic black bodies filled with plane, standing electromagnetic waves. Our
standing wave model explains the integer multiple rule of the masses of the
neutral mesons and baryons of the -branch and uses nothing else but
photons. Our results justify the cubic lattice assumption.Comment: 6 pages; 2 figure
Apparatus for real-time acoustic imaging of Rayleigh-Benard convection
We have designed and built an apparatus for real-time acoustic imaging of
convective flow patterns in optically opaque fluids. This apparatus takes
advantage of recent advances in two-dimensional ultrasound transducer array
technology; it employs a modified version of a commercially available
ultrasound camera, similar to those employed in non-destructive testing of
solids. Images of convection patterns are generated by observing the lateral
variation of the temperature dependent speed of sound via refraction of
acoustic plane waves passing vertically through the fluid layer. The apparatus
has been validated by observing convection rolls in both silicone oil and
ferrofluid.Comment: 20 pages, 11 figures, submitted to the Review of Scientific
Instrument
SPUTTER DEPTH PROFILING OF OPTICAL WAVEGUIDES USING SECONDARY ION MASS SPECTROMETRY
The technique of sputter depth profiling by means of secondary ion mass spectrometry
of samples with high resistivity is reviewed. As examples we discuss optical waveguides made
in lithium niobate by titanium indiffusion and implantation and also yttrium iron garnet
waveguides grown by liquid phase epitaxy on gadolinium gallium garnet. Depth profiling of
these waveguide structures has been performed and the necessary precautions to prevent
charging by the primary ion beam are discussed. In some cases, coating with a metallic layer
is adequate, but a more universal method is charge neutralization by an additional electron
beam
Combined population dynamics and entropy modelling supports patient stratification in chronic myeloid leukemia
Modelling the parameters of multistep carcinogenesis is key for a better understanding of cancer
progression, biomarker identification and the design of individualized therapies. Using chronic
myeloid leukemia (CML) as a paradigm for hierarchical disease evolution we show that combined
population dynamic modelling and CML patient biopsy genomic analysis enables patient stratification
at unprecedented resolution. Linking CD34+ similarity as a disease progression marker to patientderived
gene expression entropy separated established CML progression stages and uncovered
additional heterogeneity within disease stages. Importantly, our patient data informed model enables
quantitative approximation of individual patients’ disease history within chronic phase (CP) and
significantly separates “early” from “late” CP. Our findings provide a novel rationale for personalized
and genome-informed disease progression risk assessment that is independent and complementary to
conventional measures of CML disease burden and prognosis
Rhombic Patterns: Broken Hexagonal Symmetry
Landau-Ginzburg equations derived to conserve two-dimensional spatial symmetries lead to the prediction that rhombic arrays with characteristic angles slightly differ from 60 degrees should form in many systems. Beyond the bifurcation from the uniform state to patterns, rhombic patterns are linearly stable for a band of angles near the 60 degrees angle of regular hexagons. Experiments conducted on a reaction-diffusion system involving a chlorite-iodide-malonic acid reaction yield rhombic patterns in good accord with the theory.Energy Laboratory of the University of HoustonOffice of Naval ResearchU.S. Department of Energy Office of Basic Energy SciencesRobert A. Welch FoundationCenter for Nonlinear Dynamic
The SCLtTAxBCR-ABL transgenic mouse model closely reflects the differential effects of dasatinib on normal and malignant hematopoiesis in chronic phase-CML patients
The second generation tyrosine kinase inhibitor (TKI) dasatinib is a clinically approved drug for chronic myeloid leukemia (CML) as well as Ph+ acute lymphoblastic leukemia. In addition to its antileukemic effects, dasatinib was shown to impact on normal hematopoiesis and cells of the immune system. Due to the fact that the murine in vivo studies so far have not been performed in a chronic-phase CML model under steady-state conditions, our aim was to study the hematopoietic effects of dasatinib (20 mg/kg p.o.) in BCR-ABL expressing SCLtTAxBCR-ABL double transgenic (dtg) mice. Dasatinib robustly antagonized the CML phenotype in vivo in our transgenic mouse model, and this effect included both mature and immature cell populations. However, similar to patients with CML, the fraction of Lin(neg)Sca-1(+)KIT(+)CD48(neg)CD150(+) hematopoietic stem cells was not reduced by dasatinib treatment, suggesting that these cells are not oncogene-addicted. Moreover, we observed differential effects of dasatinib in these animals as compared to wild-type (wt) animals: while granulocytes were significantly reduced in dtg animals, they were increased in wt mice. And Ter119(+) erythrocytic and B220(+) B cells were increased in dtg mice but decreased in wt mice. Finally, while dasatinib induced a shift from CD49b/NK1.1 positive NK cells from the bone marrow to the spleen in wt animals, there was no change in dtg mice. In conclusion, the present mouse model provides a useful tool to study mechanisms of TKI resistance and dasatinib-associated beneficial effects and adverse events.Peer reviewe
Transition from the Couette-Taylor system to the plane Couette system
We discuss the flow between concentric rotating cylinders in the limit of
large radii where the system approaches plane Couette flow. We discuss how in
this limit the linear instability that leads to the formation of Taylor
vortices is lost and how the character of the transition approaches that of
planar shear flows. In particular, a parameter regime is identified where
fractal distributions of life times and spatiotemporal intermittency occur.
Experiments in this regime should allow to study the characteristics of shear
flow turbulence in a closed flow geometry.Comment: 5 pages, 5 figure
- …