67 research outputs found
Temperature dependence of the superconducting gap anisotropy in BiSrCaCuO
We present the first detailed data of the momentum-resolved, temperature
dependence of the superconducting gap of ,
complemented by similar data on the intensity of the photoemission
superconducting condensate spectral area. The gap anisotropy between the
and directions increases markedly with increasing
temperature, contrary to what happens for conventional anisotropic-gap
superconductors such as lead. Specifically, the size of the superconducting gap
along the direction decreases to values indistinguishable from zero
at temperatures for which the gap retains virtually full value along the
direction.Comment: APS_REVTEX. 19 pages, including 8 figures, available upon request.
UW-Madison preprin
Observation of a van Hove Singularity in with Angle Resolved Photoemission
We have performed high energy resolution angle-resolved photoemission studies
of the normal state band structure of oxygen overdoped
. We find that there is an extended saddle
point singularity in the density of states along direction.
The data also indicate that there is an asymmetry in the Fermi surface for both
the and perpendicular directions.Comment: APS_Revtex. 28 pages, including 16 figures, available upon request.
UW-Madison preprint#
Milk supplementation facilitates appetite control in obese women during weight loss:a randomized single-blind controlled trial
Effect of Iodine Doping on BiSrCaCuO: Charge Transfer or Interlayer Coupling?
A comparative study has been made of iodine-intercalated
BiSrCaCuO single crystal and 1 atm O
annealed BiSrCaCuO single crystal using AC
susceptibility measurement, X-ray photoemission (XPS) and angle-resolved
ultraviolet photoemission spectroscopy (ARUPS). AC susceptibility measurement
indicates that O-doped samples studied have T of 84 K,
whereas T of Iodine-doped samples studied are 80 K. XPS Cu 2p core
level data establish that the hole concentration in the CuO planes are
essentially the same for these two kinds of samples. ARUPS measurements show
that electronic structure of the normal states near the Fermi level has been
strongly affected by iodine intercalation. We conclude that the dominant effect
of iodine doping is to alter the interlayer coupling.Comment: LBL 9 pages, APS_Revtex. 5 Figures, available upon request.
UW-Madison preprin
Diffusion in pores and its dependence on boundary conditions
We study the influence of the boundary conditions at the solid liquid
interface on diffusion in a confined fluid. Using an hydrodynamic approach, we
compute numerical estimates for the diffusion of a particle confined between
two planes. Partial slip is shown to significantly influence the diffusion
coefficient near a wall. Analytical expressions are derived in the low and high
confinement limits, and are in good agreement with numerical results. These
calculations indicate that diffusion of tagged particles could be used as a
sensitive probe of the solid-liquid boundary conditions.Comment: soumis \`a J.Phys. Cond. Matt. special issue on "Diffusion in
Liquids, Polymers, Biophysics and Chemical Dynamics
and Oxygen Stoichiometry: Structure, Resistivity, Fermi Surface Topology and Normal State Properties
(2212) single crystal samples
were studied using transmission electron microscopy (TEM), plane
() and axis () resistivity, and high resolution
angle-resolved ultraviolet photoemission spectroscopy (ARUPS). TEM reveals that
the modulation in the axis for doped 2212 is dominantly
of type that is not sensitive to the oxygen content of the system, and the
system clearly shows a structure of orthorhombic symmetry. Oxygen annealed
samples exhibit a much lower axis resistivity and a resistivity minimum at
K. He-annealed samples exhibit a much higher axis resistivity and
behavior below 300K. The Fermi surface (FS) of oxygen annealed
2212 mapped out by ARUPS has a pocket in the FS around the
point and exhibits orthorhombic symmetry. There are flat, parallel sections of
the FS, about 60\% of the maximum possible along , and about 30\%
along . The wavevectors connecting the flat sections are about
along , and about along , rather than . The symmetry of the near-Fermi-energy dispersing
states in the normal state changes between oxygen-annealed and He-annealed
samples.Comment: APS_REVTEX 3.0, 49 pages, including 11 figures, available upon
request. Submitted to Phys. Rev. B
Experimental investigation of heat transport in homogeneous bubbly flow
In this work we study the heat transport in inhomogeneous bubbly flow. The experiments were performed in a rectangular bubble column heated from one side wall and cooled from the other, with millimetric bubbles introduced through one half of the injection section (close to the hot wall or close to the cold wall). We characterise the global heat transport while varying two parameters: the gas volume fraction , and the Rayleigh number . As captured by imaging and characterised using Laser Doppler Anemometry (LDA), different flow regimes occur with increasing gas flow rates. In the generated inhomogeneous bubbly flow there are three main contributions to the mixing: (i) transport by the buoyancy driven recirculation, (ii) bubble induced turbulence (BIT) and (iii) shear-induced turbulence (SIT). The strength of these contributions and their interplay depends on the gas volume fraction which is reflected in the measured heat transport enhancement. We compare our results with the findings for heat transport in homogeneous bubbly flow from Gvozdić et al. (2018). We find that for the lower gas volume fractions (), inhomogeneous bubbly injection results in better heat transport due to induced large-scale circulation. In contrast, for , when the contribution of SIT becomes stronger, but so does the competition between all three contributions, the homogeneous injection is more efficient
Twente mass and heat transfer water tunnel: Temperature controlled turbulent multiphase channel flow with heat and mass transfer
A new vertical water tunnel with global temperature control and the possibility for bubble and local heat and mass injection has been designed and constructed. The new facility offers the possibility to accurately study heat and mass transfer in turbulent multiphase flow (gas volume fraction up to 8%) with a Reynolds-number range from 1.5 × 104 to 3 × 105 in the case of water at room temperature. The tunnel is made of high-grade stainless steel permitting the use of salt solutions in excess of 15% mass fraction. The tunnel has a volume of 300 l. The tunnel has three interchangeable measurement sections of 1 m height but with different cross sections (0.3 × 0.04 m2, 0.3 × 0.06 m2, and 0.3 × 0.08 m2). The glass vertical measurement sections allow for optical access to the flow, enabling techniques such as laser Doppler anemometry, particle image velocimetry, particle tracking velocimetry, and laser-induced fluorescent imaging. Local sensors can be introduced from the top and can be traversed using a built-in traverse system, allowing, for example, local temperature, hot-wire, or local phase measurements. Combined with simultaneous velocity measurements, the local heat flux in single phase and two phase turbulent flows can thus be studied quantitatively and precisel
French Pregnancy Physical Activity Questionnaire Compared with an Accelerometer Cut Point to Classify Physical Activity among Pregnant Obese Women
Given the high risk for inactivity during pregnancy in obese women, validated questionnaires for physical activity (PA) assessment in this specific population is required before evaluating the effect of PA on perinatal outcomes. No questionnaire was validated in pregnant obese women. The Pregnancy Physical Activity Questionnaire (PPAQ) has been designed based on activities reported during pregnancy and validated in pregnant women. We translated the PPAQ to French and assessed reliability and accuracy of this French version among pregnant obese women. In this cross-sectional study, pregnant obese women were evenly recruited at the end of each trimester of pregnancy. They completed the PPAQ twice, with an interval of 7 days in-between, to recall PA of the last three months. Between PPAQ assessments, participants wore an accelerometer (Actigraph GT1M) during 7 consecutive days. Fourty-nine (49) pregnant obese women (29.8±4.2 yrs, 34.7±5.1 kg.m−2) participated to the study. The intraclass correlation coefficients (ICCs) between the two PPAQ assessments were 0.90 for total activity, 0.86 for light and for moderate intensity, and 0.81 for vigorous intensity activities. It ranged from 0.59 for “Transportation” to 0.89 for “Household and Caregiving” activities. Spearman correlation coefficients (SCCs) between the PPAQ and the Matthews’ cut point used to classify an activity of moderate and above intensity were 0.50 for total activity, 0.25 for vigorous intensity and 0.40 for moderate intensity. The correlations between the PPAQ and the accelerometer counts were 0.58 for total activity, 0.39 for vigorous intensity and 0.49 for moderate intensity. The highest SCCs were for “Occupation” and “Household and Caregiving” activities. Comparisons with other standard cutpoints were presented in files S1, S2, S3, S4, S5, S6, S7. The PPAQ is reliable and moderately accurate for the measure of PA of various intensities and types among pregnant obese women
Hypersensitive Response-Like Reaction Is Associated with Hybrid Necrosis in Interspecific Crosses between Tetraploid Wheat and Aegilops tauschii Coss
BACKGROUND: Hybrid speciation is classified into homoploid and polyploid based on ploidy level. Common wheat is an allohexaploid species that originated from a naturally occurring interploidy cross between tetraploid wheat and diploid wild wheat Aegilops tauschii Coss. Aegilops tauschii provides wide naturally occurring genetic variation. Sometimes its triploid hybrids with tetraploid wheat show the following four types of hybrid growth abnormalities: types II and III hybrid necrosis, hybrid chlorosis, and severe growth abortion. The growth abnormalities in the triploid hybrids could act as postzygotic hybridization barriers to prevent formation of hexaploid wheat. METHODOLOGY/PRINCIPAL FINDINGS: Here, we report on the geographical and phylogenetic distribution of Ae. tauschii accessions inducing the hybrid growth abnormalities and showed that they are widely distributed across growth habitats in Ae. tauschii. Molecular and cytological characterization of the type III necrosis phenotype was performed. The hybrid abnormality causing accessions were widely distributed across growth habitats in Ae. tauschii. Transcriptome analysis showed that a number of defense-related genes such as pathogenesis-related genes were highly up-regulated in the type III necrosis lines. Transmission electron microscope observation revealed that cell death occurred accompanied by generation of reactive oxygen species in leaves undergoing type III necrosis. The reduction of photosynthetic activity occurred prior to the appearance of necrotic symptoms on the leaves exhibiting hybrid necrosis. CONCLUSIONS/SIGNIFICANCE: Taking these results together strongly suggests that an autoimmune response might be triggered by intergenomic incompatibility between the tetraploid wheat and Ae. tauschii genomes in type III necrosis, and that genetically programmed cell death could be regarded as a hypersensitive response-like cell death similar to that observed in Arabidopsis intraspecific and Nicotiana interspecific hybrids. Only Ae. tauschii accessions without such inhibiting factors could be candidates for the D-genome donor for the present hexaploid wheat
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