15,359 research outputs found
Experimental results for propagation of diffuse photon-density waves up to 1 GHz in a tissue-like medium containing an absorbing edge
No full textOptical imaging in the near-infrared (NIR) region provides the possibility to detect and determine pathological changes in human tissue without the drawback of ionizing radiation and with little technical and financial effort. Especially in rheumatoid arthritis, imaging by optical tomography to detect early inflammations in joints has the potential to become a supportive tool to common imaging modalities. One way to enhance the resolution and specificity of optical tissue characterization is to use the frequency domain instead of DC intensity measurement. Intensity modulation of a light source leads to propagation of diffuse photon-density waves (PDW) through the tissue. In this study, we report basic experimental results on tissuelike phantoms to determine the optimal parameters for PDW-transillumination of finger joints. We used PDW with modulation frequencies from 100 MHz up to 1 GHz to scan across a tissuelike phantom containing an absorbing plane bounded by an edge. The geometrical extents of the phantoms are similar to human finger joints. We measure the transmitted PDW and show that amplitude and phase behaves at the edge as expected according to theoretical predictions. An increasing modulation frequency leads to increasing slope of the amplitude decay at the edge but decreasing signal-to-noise ratio. Even at 1 GHz, the edge is detectable
Signal-to-noise analysis for propagation of laser radiation through a tissue-like medium by diffuse photon-density waves
No full textBiomedical optical imaging in the near-infrared (NIR) region provides the possibility to detect and determine pathological and functional changes in human tissue without the drawback of ionizing radiation. Of special promise is the application of this technology for the detection of joint diseases, such as rheumatoid arthritis (RA). It has been shown that optical changes in the synovial fluid and the vasculature surrounding the joints can be detected with optical methods. Applying optical tomographic methods one should be able to localize and quantify these changes for detection of the onset of RA. The first studies have been limited to continuous wave imaging. However, it is well known that enhanced resolution and better separation between absorption and scattering properties of tissue can be achieved using intensity modulated light sources. Intensity modulation of laser light in the MHz region leads to propagation of so-called diffuse photon density waves (PDW) through the tissue In this study we report on basic experimental results to determine performance and sensitivity of PDW-transillumination of tissue like phantoms. We used a vector network analyzer to generate and analyze intensity modulation from 100 MHz up to 1 GHz via a diode laser and an avalanche photo diode. Scans were performed across phantoms containing a layer with different absorbing and scattering properties bounded by an edge. The thickness of the phantoms was chosen similar to human fingers to gain information for optimization of tomographic imaging of finger joints. We experimentally determined the signal-to-noise ratio (SNR) of the system and compared the results to theoretical predictions. Noise and SNR of amplitude and phase depend on frequency of modulation. While the amplitude SNR decreases with frequency, phase SNR increases to assume a maximum value. We found that the inserted layer can be better characterized using phase information, which becomes more valuable as the source modulation frequency is increased. On the other hand, the sensitivity to perturbations is highest in the amplitude data obtained at lower frequencies. Thus, for tomographic imaging, optimal modulation frequencies should be found depending on the tissue type and nature of tissue inhomogeneities
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
Measurement of the branching fraction
No full textThe B
0
s
→ J/ψK
0
S
branching fraction is measured in a data sample corresponding to 0.41 fb−1
of integrated luminosity collected with the LHCb detector at the LHC. This channel is sensitive to
the penguin contributions affecting the sin 2β measurement from B
0
→ J/ψK
0
S
. The time-integrated
branching fraction is measured to be B(B
0
s
→ J/ψK
0
S
) = (1.83±0.28)×10−5
. This is the most precise
measurement to date
The developmental morphology of Leea guineensis. II. Floral development
No full textPT: J; CR: BENNEK C, 1958, BOT JB SYST, V77, P423 BUGNON F, 1953, PUBLICATION U DIJON, V11 CRONQUIST A, 1981, INTEGRATED SYSTEM CL CRONQUIST A, 1988, EVOLUTION CLASSIFICA DAHLGREN RMT, 1980, BOTANICAL J LINNEAN, V80, P91 ERDTMAN G, 1966, POLLEN MORPHOLOGY PL, V1 GAGNEPAIN MF, 1910, B SOC BOT FR, V57, P331 GERRATH JM, 1988, ASPECTS FLORAL DEV, P121 GERRATH JM, 1988, CAN J BOT, V66, P1334 GERRATH JM, 1988, CAN J BOT, V66, P209 GERRATH JM, 1988, THESIS U GUELPH GUEL GERRATH JM, 1989, CAN J BOT, V67, P1356 GERRATH JM, 1989, CAN J BOT, V67, P2371 GERRATH JM, 1989, CAN J BOT, V67, P803 HEYWOOD VH, 1978, FLOWERING PLANTS WOR LACROIX CR, 1990, BOT GAZ, V151, P204 LATIFF A, 1984, 4 U KEB COLL WORK PA, P33 MEDAN D, 1988, ASPECTS FLORAL DEV, P133 NAIR NC, 1957, WILD BOT NOT, V110, P160 NAIR NC, 1968, J INDIAN BOT SOC, V47, P193 POSLUSZNY U, 1980, CAN J BOT, V58, P2491 POSLUSZNY U, 1986, CAN J BOT, V64, P1620 RISDALE CE, 1974, BLUMEA, V22, P57 SATTLER R, 1973, ORGANOGENESIS FLOWER SMITH AC, 1985, FLORA VITIENSIS NOVA, V3, P712 SUSSENGUTH K, 1953, NATURLICHEN PFLANZ D, V20, P372 TARNAVSCHI IT, 1968, POLLEN SPORES, V10, P221 TOELKEN H, 1983, FLOWERING PLANTS AUS, P227 WILD H, 1966, FLORA ZAMBESIACA 2, V2, P492; NR: 29; TC: 6; J9: BOT GAZ; PG: 11; GA: DU901Source type: Electronic(1
Direct Numerical Simulations of Turbulent Mixing Layers Between Two Fluids of Large Density Difference
No full textIn numerous practical applications, shear layers exist between fluids of strongly differing densities. At high Atwood numbers, the large variations in density introduce important effects that have recently been observed in other flows (e.g., Livescu and Ristorcelli, J. Fluid Mech., 605:145–180, 2008). To investigate the inertial variable density effects on the instability growth and structure of mixing layers, we perform very large Direct Numerical Simulations of planar mixing layers between two miscible fluids, each with different density. The DNS domain sizes accommodate large extents of mode pairings, based on the most unstable modes obtained from linear stability analysis. The results display the overall statistical effects on the turbulence and mixing, as well as the structural differences that occur as Atwood number is varied. In particular, significant asymmetries are introduced by the differences in the densities of the mixing layer streams
Light scattering study of rheumatoid arthritis
No full textThe distribution of light scattered by finger joints is studied in the near-IR region. It is shown that variations in the optical parameters of the tissue (scattering coefficient mus, absorption coefficient mua, and anisotropy factor g) depend on the presence of the rheumatoid arthritis (RA). At the first stage, the distribution of scattered light was measured in diaphanoscopic experiments. The convolution of a Gaussian error function with the scattering phase function proved to be a good approximation of the data obtained. Then, a new method was developed for the reconstruction of distribution of optical parameters in the finger cross section. Model tests of the quality of this reconstruction method show good results
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
No full textThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Self-similar regimes in Unstably Stratified Homogeneous Turbulence
No full textUnstably stratified homogeneous turbulence develops at late time a self-similar dynamics characterized by an exponential growth of turbulent quantities. It is believed from recent theoretical studies that different growth rates are possible, depending on the initial distribution of energy at large scales. In order to confirm these predictions, we run both highly resolved direct numerical simulations and a spectral model based on an eddy-damped quasi-normal closure. In addition to confirming the influence of initial conditions, our study sheds light on the anisotropic structures of the self-similar regimes
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