On Molecular Hydrogen Formation and the Magnetohydrostatic Equilibrium of Sunspots

We have investigated the problem of sunspot magnetohydrostatic equilibrium with comprehensive IR sunspot magnetic field survey observations of the highly sensitive Fe I lines at 15650 \AA\ and nearby OH lines. We have found that some sunspots show isothermal increases in umbral magnetic field strength which cannot be explained by the simplified sunspot model with a single-component ideal gas atmosphere assumed in previous investigations. Large sunspots universally display non-linear increases in magnetic pressure over temperature, while small sunspots and pores display linear behavior. The formation of molecules provides a mechanism for isothermal concentration of the umbral magnetic field, and we propose that this may explain the observed rapid increase in umbral magnetic field strength relative to temperature. Existing multi-component sunspot atmospheric models predict that a significant amount of molecular hydrogen (H2) exists in the sunspot umbra. The formation of H2 can significantly alter the thermodynamic properties of the sunspot atmosphere and may play a significant role in sunspot evolution. In addition to the survey observations, we have performed detailed chemical equilibrium calculations with full consideration of radiative transfer effects to establish OH as a proxy for H2, and demonstrate that a significant population of H2 exists in the coolest regions of large sunspots.Comment: 17 pages, 19 figures, accepted for publication in Ap

Spectroscopic properties of cool Ursa Major group members

Until now, most members of the Ursa Major (UMa) group of stars have been identified by means of kinematic criteria. However, in many cases kinematic criteria alone are insufficient to ascertain, whether an individual star is really a member of this group. Since photometric criteria are ineffective in the case of cool dwarf members, one must use spectroscopic criteria. Nevertheless, resulting membership criteria are inconclusive. We reanalyse spectroscopic properties of cool UMa group dwarfs. In particular, we study the distribution of iron abundance, the strength of the Li I absorption at 6708 A and the Li abundance, and the infilling of the core of the H alpha line. Twenty-five cool and northern bona-fide members are carefully selected from the literature. Homogeneously measured stellar parameters and iron abundances are given for all Sun-like stars selected, based on spectra of high resolution and high signal-to-noise ratio. In addition, we measure the Li equivalent width and abundance as well as the relative intensity of the H alpha core and the corresponding chromospheric flux. The studied stars infer an average Ursa Major group iron abundance of -0.03+-0.05 dex, which is higher by about 0.06 dex than determined elsewhere. The Li abundance derived of Ursa Major group dwarf stars is higher than in the Hyades at effective temperatures cooler than the Sun, but lower than in the younger Pleiades, a result which is independent of the exact value of the effective temperature adopted. The Sun-like and cooler dwarfs also display chromospheric infilling of the H alpha core. We present spectroscopic criteria that may be used to exclude non-members.Comment: accepted for publication in A&A, 19 pages, 10 figures, 7 table

Wave dynamics in a sunspot umbra

The high spatial and time resolution data obtained with SDO/AIA for the sunspot in active region NOAA 11131 on 08 December 2010 were analysed with the time-distance plot technique and the pixelised wavelet filtering method. Oscillations in the 3 min band dominate in the umbra. The integrated spectrum of umbral oscillations contains distinct narrowband peaks at 1.9 min, 2.3 min, and 2.8 min. The power significantly varies in time, forming distinct oscillation trains. The oscillation power distribution over the sunspot in the horizontal plane reveals that the enhancements of the oscillation amplitude, or wave fronts, have a distinct structure consisting of an evolving two-armed spiral and a stationary circular patch at the spiral origin, situated near the umbra centre. This structure is seen from the temperature minimum to the corona. In time, the spiral rotates anti-clockwise. The wave front spirality is most pronounced during the maximum amplitude phases of the oscillations. In the low-amplitude phases the spiral breaks into arc-shaped patches. The 2D cross-correlation function shows that the oscillations at higher atmospheric levels occur later than at lower layers. The phase speed is estimated to be about 100 km/s. The fine spectral analysis shows that the central patch corresponds to the high-frequency oscillations, while the spiral arms highlight the lower-frequency oscillations in the 3-min band. The vertical and horizontal radial structure of the oscillations is consistent with the model that interprets umbral oscillations as slow magnetoacoustic waves filtered by the atmospheric temperature non-uniformity in the presence of the magnetic field inclination from the vertical. The mechanism for the polar-angle structure of the oscillations, in particular the spirality of the wave fronts, needs to be revealed.Comment: 8 pages, 9 figures, Astronomy and Astrophysics, 201

Observations of Plasma Upflow in a Warm Loop with Hinode/EIS

A complete understanding of Doppler shift in active region loops can help probe the basic physical mechanism involved into the heating of those loops. Here we present observations of upflows in coronal loops detected in a range of temperature temperatures (log T=5.8 - 6.2). The loop was not discernible above these temperatures. The speed of upflow was strongest at the footpoint and decreased with height. The upflow speed at the footpoint was about 20 km/s in Fe VIII which decreased with temperature being about 13 km/s in Fe X, about 8 km/s in Fe XII and about 4 km/s in FeXIII. To the best of our knowledge this is the first observation providing evidence of upflow of plasma in coronal loop structures at these temperatures. We interpret these observations as evidence of chromospheric evaporation in quasi-static coronal loops.Comment: 14 pages, 5 figures, Accepted for Publication in The Astrophysical Journal Letter

Spartan Daily, April 23, 1964

Volume 51, Issue 110https://scholarworks.sjsu.edu/spartandaily/4531/thumbnail.jp

Valuing EQ-5D health states: A review and analysis, CHERE Working Paper 2007/9

Objective: To identify the key methodological issues in the construction of population-level EQ-5D / Time Trade-Off (TTO) preference elicitation studies. Study Design: This study involves three components. The first was to identify existing population-level EQ-5D TTO studies. The second was to illustrate and discuss the key areas of divergence between studies, including the international comparison of tariffs. The third was to portray the relative merits of each of the approaches, and to compare the results of studies across countries. Results: While most papers report use of the protocol developed in the original UK study, we identified three key areas of divergence in the construction and analysis of surveys. These are the number of health states valued in order to determine the algorithm for estimating all health states, the approach to valuing states worse than immediate death, and the choice of algorithm. Finally, the evidence on international comparisons suggests differences between countries, although it is difficult to disentangle differences in cultural attitudes with random error and differences due to methodological divergence. Conclusion: Differences in methods are likely to obscure true differences in values between countries. However, population-specific valuation sets for countries engaging in economic evaluation would better represent societal attitudes.health state valuation, EQ5-D

The health state preferences and logistical inconsistencies of New Zealanders: a tale of two tariffs

Notwithstanding the proposed use of Cost-Utility Analysis (CUA) to inform health care priority setting in New Zealand, to date there has been no research into New Zealanders’ valuations of health-related quality of life. This paper reports the results of a study of the health state preferences of adult New Zealanders generated from a postal survey to which 1360 people responded (a 50% response rate). The survey employed a self-completed questionnaire in which a selection of health states were described using the EQ-5D health state classification system and respondents’ valuations were sought using a visual analogue scale (VAS). Close attention is paid to the quality of the data, in particular to the ‘logical inconsistencies’ in respondents’ valuations. Regression analysis is used to interpolate values over the 245 possible EQ-5D states. Two tariffs of health state preferences, arising from contrasting treatments of the logical inconsistencies, are reported.New Zealand, EuroQol, EQ-5D

A Generalization of Multiplication Table

In this note, we generalize the concept of multiplication table by connecting with lattice points. Then we introduce and proof a generalization of Erdös multiplication table theorem

Human performance control monitoring systems Interim report no. 2

Computer program to simulate second order servo system dynamics under automatic and manual contro