Validated helioseismic inversions for 3-D vector flows

According to time-distance helioseismology, information about internal fluid motions is encoded in the travel times of solar waves. The inverse problem consists of inferring 3-D vector flows from a set of travel-time measurements. Here we investigate the potential of time-distance helioseismology to infer 3-D convective velocities in the near-surface layers of the Sun. We developed a new Subtractive Optimally Localised Averaging (SOLA) code suitable for pipeline pseudo-automatic processing. Compared to its predecessor, the code was improved by accounting for additional constraints in order to get the right answer within a given noise level. The main aim of this study is to validate results obtained by our inversion code. We simulate travel-time maps using a snapshot from a numerical simulation of solar convective flows, realistic Born travel-time sensitivity kernels, and a realistic model of travel-time noise. These synthetic travel times are inverted for flows and the results compared with the known input flow field. Additional constraints are implemented in the inversion: cross-talk minimization between flow components and spatial localization of inversion coefficients. Using modes f, p1 through p4, we show that horizontal convective flow velocities can be inferred without bias, at a signal-to-noise ratio greater than one in the top 3.5 Mm, provided that observations span at least four days. The vertical component of velocity (v_z), if it were to be weak, is more difficult to infer and is seriously affected by cross-talk from horizontal velocity components. We emphasise that this cross-talk must be explicitly minimised in order to retrieve v_z in the top 1 Mm. We also show that statistical averaging over many different areas of the Sun allows for reliably measuring of average properties of all three flow components in the top 5.5 Mm of the convection zone.Comment: 14 pages main paper, 9 pages electronic supplement, 28 figures. Accepted for publication in Astronomy & Astrophysic

Probing sunspots with two-skip time-distance helioseismology

Previous helioseismology of sunspots has been sensitive to both the structural and magnetic aspects of sunspot structure. We aim to develop a technique that is insensitive to the magnetic component so the two aspects can be more readily separated. We study waves reflected almost vertically from the underside of a sunspot. Time-distance helioseismology was used to measure travel times for the waves. Ray theory and a detailed sunspot model were used to calculate travel times for comparison. It is shown that these large distance waves are insensitive to the magnetic field in the sunspot. The largest travel time differences for any solar phenomena are observed. With sufficient modeling effort, these should lead to better understanding of sunspot structure

Greater Forearm Blood Flow is Associated With Higher Physical Activity in Older Individuals

Please refer to the pdf version of the abstract located adjacent to the title

Phylogenetics of Paniceae (Poaceae)

Paniceae demonstrate unique variability of photosynthetic physiology and anatomy, including both non-Kranz and Kranz species and all subtypes of the latter. This variability suggests hypotheses of independent origin or reversals (e.g., from C4 to C3). These hypotheses can be tested by phylogenetic analysis of independent molecular characters. The molecular phylogeny of 57 species of Paniceae was explored using sequences from the grass-specific insert found in the plastid locus rpoC2. Phylogenetic analyses confirmed some long-recognized alliances in Paniceae, some recent molecular phylogenetic results, and suggested new relationships. Broadly, Paniceae were found to be paraphyletic with Andropogoneae, Panicum was found to be polyphyletic, and Oplismenus hirtellus was resolved as the sister group to the remaining ingroup species. A particularly well-supported clade in the rpoC2 tree included four genera with non-Kranz species and three with distinctively keeled paleas. As previously suggested, the PCK (phosphoenol pyruvate carboxykinase) C4 subtype arose once within Paniceae. All clades with non-Kranz species had Kranz ancestors or sister taxa suggesting repeated loss of the Kranz syndrome

State Legislative Update

The purpose of this Bill is to provide an alternative approach for individuals with a cause of action against a municipality.\u27 Rather than the costly and time-consuming traditional method of hiring an attorney and filing a lawsuit, House Bill 2631 offers individuals an opportunity for Alternative Dispute Resolution ( ADR ) in the form of arbitration. The Bill would allow any individual with a claim in contract or tort against a municipality to require the municipality to submit to the arbitration of the claim. The purpose of House Bill 2631 is to facilitate the resolution of individual claims against a city. However, a fundamental principle of arbitration is that it is a matter of contract, and no party should be forced into the arbitration of a claim which they have not agreed to arbitrate

Parents' Sense of “Entitlement” in Adoptive and Nonadoptive Families

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72242/1/j.1545-5300.1996.00441.x.pd

Balltracking: an highly efficient method for tracking flow fields

We present a method for tracking solar photospheric flows that is highly efficient, and demonstrate it using high resolution MDI continuum images. The method involves making a surface from the photospheric granulation data, and allowing many small floating tracers or balls to be moved around by the evolving granulation pattern. The results are tested against synthesised granulation with known flow fields and compared to the results produced by Local Correlation tracking (LCT). The results from this new method have similar accuracy to those produced by LCT. We also investigate the maximum spatial and temporal resolution of the velocity field that it is possible to extract, based on the statistical properties of the granulation data. We conclude that both methods produce results that are close to the maximum resolution possible from granulation data. The code runs very significantly faster than our similarly optimised LCT code, making real time applications on large data sets possible. The tracking method is not limited to photospheric flows, and will also work on any velocity field where there are visible moving features of known scale length

Scattering of the f-mode by small magnetic flux elements from observations and numerical simulations

The scattering of f-modes by magnetic tubes is analyzed using three-dimensional numerical simulations. An f-mode wave packet is propagated through a solar atmosphere embedded with three different flux tube models which differ in radius and total magnetic flux. A quiet Sun simulation without a tube present is also performed as a reference. Waves are excited inside the flux tube and propagate along the field lines, and jacket modes are generated in the surroundings of the flux tube, carrying 40% as much energy as the tube modes. The resulting scattered wave is mainly an f-mode composed of a mixture of m=0 and m=+/-1 modes. The amplitude of the scattered wave approximately scales with the magnetic flux. A small amount of power is scattered into the p_1-mode. We have evaluated the absorption and phase shift from a Fourier-Hankel decomposition of the photospheric vertical velocities. They are compared with the results obtained from the emsemble average of 3400 small magnetic elements observed in high-resolution MDI Doppler datacubes. The comparison shows that the observed dependence of the phase shift with wavenumber can be matched reasonably well with the simulated flux tube model. The observed variation of the phase-shifts with the azimuthal order $m$ appears to depend on details of the ensemble averaging, including possible motions of the magnetic elements and asymmetrically shaped elements.Comment: Accepted for publication in The Astrophysical Journa