13,370 research outputs found
Note on finite temperature sum rules for vector and axial-vector spectral functions
An updated analysis of vector and axial-vector spectral functions is
presented. The resonant contributions to the spectral integrals are shown to be
expressible as multiples of 4 pi^2 f_pi^2, encoding the scale of spontaneous
chiral symmetry breaking in QCD. Up to order T^2 this behavior carries over to
the case of finite temperature.Comment: 10 pages, 2 figure
NetCDF model output of the entire state of the surface layer, including simulated dFe dyes, of the circum-Antarctic
Dataset: Antarctic dFe model dyesFor a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/782848NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1643652, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-164361
Solution to the problem of the poor cyclic fatigue resistance of bulk metallic glasses
The recent development of metallic glass-matrix composites represents a particular milestone in engineering materials for structural applications owing to their remarkable combination of strength and toughness. However, metallic glasses are highly susceptible to cyclic fatigue damage, and previous attempts to solve this problem have been largely disappointing. Here, we propose and demonstrate a microstructural design strategy to overcome this limitation by matching the microstructural length scales (of the second phase) to mechanical crack-length scales. Specifically, semisolid processing is used to optimize the volume fraction, morphology, and size of second-phase dendrites to confine any initial deformation (shear banding) to the glassy regions separating dendrite arms having length scales of â2 ÎŒm, i.e., to less than the critical crack size for failure. Confinement of the damage to such interdendritic regions results in enhancement of fatigue lifetimes and increases the fatigue limit by an order of magnitude, making these âdesignedâ composites as resistant to fatigue damage as high-strength steels and aluminum alloys. These design strategies can be universally applied to any other metallic glass systems
Angular Correlations in Internal Pair Conversion of Aligned Heavy Nuclei
We calculate the spatial correlation of electrons and positrons emitted by
internal pair conversion of Coulomb excited nuclei in heavy ion collisions. The
alignment or polarization of the nucleus results in an anisotropic emission of
the electron-positron pairs which is closely related to the anisotropic
emission of -rays. However, the angular correlation in the case of
internal pair conversion exhibits diverse patterns. This might be relevant when
investigating atomic processes in heavy-ion collisions performed at the Coulomb
barrier.Comment: 27 pages + 6 eps figures, uses revtex.sty and epsf.sty,
tar-compressed and uuencoded with uufile
Renormalization of the baryon axial vector current in large-N_c chiral perturbation theory
The baryon axial vector current is computed at one-loop order in heavy baryon
chiral perturbation theory in the large-N_c limit, where N_c is the number of
colors. Loop graphs with octet and decuplet intermediate states cancel to
various orders in N_c as a consequence of the large-N_c spin-flavor symmetry of
QCD baryons. These cancellations are explicitly shown for the general case of
N_f flavors of light quarks. In particular, a new generic cancellation is
identified in the renormalization of the baryon axial vector current at
one-loop order. A comparison with conventional heavy baryon chiral perturbation
theory is performed at the physical values N_c=3, N_f=3.Comment: REVTex4, 29 pages, 2 figures, 6 tables. Equations (32) and (81)
corrected. Some typos fixed. Results and conclusions remain unchange
Modeling Nutrient and Plankton Processes in the California Coastal Transition Zone: 3. Lagrangian Drifters
Two types of numerical Lagrangian drifter experiments were conducted, using a set of increasingly complex and sophisticated models, to investigate the processes associated with the plankton distributions in the California coastal transition zone (CTZ). The first experiment used a one-dimensional (1-D; vertical) time-dependent physical-bio-optical model, which contained a nine-component food web. Vertical velocities, along the track of simulated Lagrangian drifters, derived from a three-dimensional (3-D), primitive equation circulation model developed to simulate the flow observed within the CTZ; were used to parameterize the upwelling and downwelling processes. The second experiment used 880 simulated Lagrangian drifters from a 3-D primitive equation circulation model which was coupled to the same food web and bio-optical model used in the first experiment. Parameterization of the biological processes in both experiments were based upon data obtained during the CTZ field experiments. Comparison of simulations with data provided insight into the role of the biological and physical processes in determining the development of the subsurface chlorophyll maximum and other related features. In both studies, the vertical velocities experienced by a simulated Lagrangian drifter as it was advected offshore while entrained within a filament played a major role in determining the depth to which the euphotic zone and the chlorophyll maximum developed. Also, as the drifters moved offshore, the food web changed from a coastal, neritic food web to an offshore, oligotrophic food web due to the decrease in nutrient availability. The temporal development of the food web constituents following the simulated drifters was dependent upon the environment to which the drifter was exposed. For example, the amount of time upwelled or downwelled and the initial location in the CTZ region greatly affected the development of the food web
Modeling Nutrient and Plankton Processes in the California Coastal Transition Zone: 1. A Time- and Depth-Dependent Model
A time- and depth-dependent, physical-bio-optical model was developed for the California coastal transition zone (CTZ) with the overall objective of understanding and quantifying the processes that contribute to the vertical and temporal development of nutrient and plankton distributions in the CTZ. The model food web components included silicate, nitrate, ammonium, two phytoplankton size fractions, copepods, doliolids, euphausiids, and a detritus pool. The wavelength-dependent subsurface irradiance field was attenuated by sea water and phytoplankton pigments. The one-dimensional (1-D) model adequately simulated the development and maintenance of a subsurface chlorophyll maximum in different regions within the CTZ. An analysis of the individual terms in the model governing equations revealed that phytoplankton in situ growth was primarily responsible for the creation and maintenance of the subsurface chlorophyll maximum at both coastal and oceanic regions in the CTZ. The depth to which the maximum in situ growth occurred was controlled by the combined effect of light and nutrient limitation. Also, the simulated bio-optical fields demonstrated the effect of nonlinear couplings between food web components and the subsurface irradiance field on vertical biological distributions. In particular, the epsilon-folding scale of the subsurface photosynthetically available radiation (PAR) was influenced by the level of zooplankton grazing
R\uf6tliche L\ue4sion am Stamm
Anamnese 1
Ein 65-j\ue4hriger Patient, der im Gesichtsbereich bereits chronische Lichtsch\ue4den aufwies, wurde im Rahmen des Nierentransplantationsscreenings wegen einer neu aufgetretenen r\uf6tlichen L\ue4sion in unserer Ambulanz vorstellig. Der Patient selbst bemerkte die L\ue4sion nicht.
Anamnese 2
Eine 59-j\ue4hrige Patientin kam wegen multipler N\ue4vi zur allj\ue4hrlichen Routinekontrolle. Die neu aufgetretene r\uf6tliche Papel am R\ufccken rechts war ihr nicht aufgefallen
Electron-phonon coupling in potassium-doped graphene: Angle-resolved photoemission spectroscopy
The electron-phonon coupling in potassium-doped graphene on Ir(111) is
studied via the renormalization of the pi* band near the Fermi level, using
angle-resolved photoemission spectroscopy. The renormalization is found to be
fairly weak and almost isotropic, with a mass enhancement parameter of lambda=
0.28(6) for both the K-M and the K-G direction. These results are found to
agree well with recent first principles calculations.Comment: 5 pages, 3 figure
Scalar Field Theory with a Non-Standard Potential
We study the phase structure of a 4D complex scalar field theory with a
potential V(Phi) = | Lambda^3 / Phi - Lambda Phi |^2 at zero and at finite
temperature. The model is analyzed by mean field and Monte Carlo methods. At
zero temperature the theory falls in the universality class of the 4D Ising
model when varying Lambda. The situation is less clear-cut for variations
w.r.t. Lambda at large temperatures and variations w.r.t. temperature at a
given value of Lambda. We observe temperature independence of the mass of the
first excitation.Comment: 24 pages, 9 figures; version published in Phys. Rev. D 7
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