Measuring the Hidden Aspects of Solar Magnetism

2008 marks the 100th anniversary of the discovery of astrophysical magnetic fields, when George Ellery Hale recorded the Zeeman splitting of spectral lines in sunspots. With the introduction of Babcock's photoelectric magnetograph it soon became clear that the Sun's magnetic field outside sunspots is extremely structured. The field strengths that were measured were found to get larger when the spatial resolution was improved. It was therefore necessary to come up with methods to go beyond the spatial resolution limit and diagnose the intrinsic magnetic-field properties without dependence on the quality of the telescope used. The line-ratio technique that was developed in the early 1970s revealed a picture where most flux that we see in magnetograms originates in highly bundled, kG fields with a tiny volume filling factor. This led to interpretations in terms of discrete, strong-field magnetic flux tubes embedded in a rather field-free medium, and a whole industry of flux tube models at increasing levels of sophistication. This magnetic-field paradigm has now been shattered with the advent of high-precision imaging polarimeters that allow us to apply the so-called "Second Solar Spectrum" to diagnose aspects of solar magnetism that have been hidden to Zeeman diagnostics. It is found that the bulk of the photospheric volume is seething with intermediately strong, tangled fields. In the new paradigm the field behaves like a fractal with a high degree of self-similarity, spanning about 8 orders of magnitude in scale size, down to scales of order 10 m.Comment: To appear in "Magnetic Coupling between the Interior and the Atmosphere of the Sun", eds. S.S. Hasan and R.J. Rutten, Astrophysics and Space Science Proceedings, Springer-Verlag, Heidelberg, Berlin, 200

Assessment of Climate Events in Changma Season (Korean Monsoon) for Production Trend of Sorghum-Sudangrass Hybrid (\u3ci\u3eSorghum bicolor\u3c/i\u3e L.) in the Central Inland Regions of Korea Using Time Series Analysis

This study aimed to assess the impact of climate events in the Changma (Korean Monsoon) season on the production trend of sorghum-sudangrass hybrid (SSH) in central inland regions using time series analysis. The dataset in Suwon from 1988–2013 (n = 388) was generated by merging SSH data and climate data. The accumulated temperature (SHAT, ℃), rainfall amount (SHRA, mm) and sunshine duration (SHSD, hr) from seeding to harvesting were used to assess their impact on the trend of dry matter yield (DMY, kg/ha) for SSH. Furthermore, heavy rainfall (HRF) and typhoons (TPH) were considered as climate events. As a result, the impact of climate events did not affect DMY, even though the frequency and intensity of HRF increased. Conversely, SHAT and SHRA had positive and negative effects on the trend of DMY, respectively. Therefore, the DMY trend of SSH was forecasted to increase until 2045, unlike maize, which has shown a declining trend. The forecasted DMY in 2045 was 14,926 kg/ha. It is likely that the damage by heavy rainfall and typhoons was reduced due to multiple-harvesting and a deeper extension of the root system. Therefore, in an environment that is rapidly changing due to climate change and abnormal weather, such as the Changma season, the cultivation of SSH would be advantageous as it would ensure a stable and robust yield

Assessment of Causality between Climate Variables and Production for Whole Crop Maize Using Structural Equation Modeling

This study aimed to assess the causality of different climate variables on the production of whole crop maize silage (Zea mays L.; WCM) in the central inland region of the Republic of Korea. Furthermore, the effect of these climate variables was also determined by looking at direct and indirect pathways during the stages before and after silking. The WCM metadata (n = 640) were collected from the Rural Development Administration’s reports of new variety adaptability from 1985‒2011 (27 years). The climate data was collected based on year and location from the Korean Meteorology Administration’s weather information system. Causality, in this study, was defined by various cause-and-effect relationships between climatic factors, such as temperature, rainfall amount, sunshine duration, wind speed and relative humidity in the seeding to silking stage and the silking to harvesting stage. All climate variables except wind speed were different before and after the silking stage, which indicates the silking occurred during the period when the Korean season changed from spring to summer. Therefore, the structure of causality was constructed by taking account of the climate variables that were divided by the silking stage. In particular, the indirect effect of rainfall through the appropriate temperature range was different before and after the silking stage. The damage caused by heat-humidity was having effect before the silking stage while the damage caused by night-heat was not affecting WCM production. There was a large variation in soil surface temperature and rainfall before and after the silking stage. Over 350 mm of rainfall affected dry matter yield (DMY) when soil surface temperatures were less than 22℃ before the silking stage. Over 900 mm of rainfall also affected DMY when soil surface temperatures were over 27℃ after the silking stage. For the longitudinal effects of soil surface temperature and rainfall amount, less than 22℃ soil surface temperature and over 300 mm of rainfall before the silking stage affected yield through over 26℃ soil surface temperature and less than 900 mm rainfall after the silking stage, respectively

Impact of Abnormal Climate Events on the Production of Italian Ryegrass as a Season in the Republic of Korea

This study aimed to assess the impact of abnormal climate events on the production of Italian ryegrass (IRG), such as autumn low-temperature, severe winter cold and spring droughts in the central inland, southern inland and southern coastal regions. Seasonal climatic variables, including temperature, precipitation, wind speed, relative humidity, and sunshine duration, were used to set the abnormal climate events using principal component analysis, and the abnormal climate events were distinguished from normal using Euclidean-distance cluster analysis. Furthermore, to estimate the impact caused by abnormal climate events, the dry matter yield (DMY) of IRG between abnormal and normal climate events was compared using a t-test with 5% significance level. As a result, the impact to the DMY of IRG by abnormal climate events in the central inland of Korea was significantly large in order of severe winter cold, spring drought, and autumn low temperature. In the southern inland regions, severe winter cold was also the most serious abnormal event. These results indicate that the severe cold is critical to IRG in inland regions. Meanwhile, in the southern coastal regions, where severe cold weather is rare, the spring drought was the most serious abnormal climate event. In particular, since 2005, the frequency of spring droughts has tended to increase. In consideration of the trend and frequency of spring drought events, it is likely that drought becomes a NEW NORMAL during spring in Korea. This study was carried out to assess the impact of seasonal abnormal climate events on the DMY of IRG, and it can be helpful to make a guideline for its vulnerability. This study was accepted in the Journal of Animal Science and Technology in 02/NOV/2020

The Milky Way's stellar halo - lumpy or triaxial?

We present minimum chi-squared fits of power law and Hernquist density profiles to F-turnoff stars in eight 2.5 deg wide stripes of SDSS data: five in the North Galactic Cap and three in the South Galactic cap. Portions of the stellar Galactic halo that are known to contain large streams of tidal debris or other lumpy structure, or that may include significant contamination from the thick disk, are avoided. The data strongly favor a model that is not symmetric about the Galaxy's axis of rotation. If included as a free parameter, the best fit to the center of the spheroid is surprisingly approx 3 kpc from the Galactic center in the direction of the Sun's motion. The model fits favor a low value of the density of halo stars at the solar position. The alternative to a non-axisymmetric stellar distribution is that our fits are contaminated by previously unidentified lumpy substructure.Comment: 10 pages, 10 figs, to appear in proceedings of conference "Physics at the end of the Galactic Cosmic Ray Spectrum", Journal of Physics: Conf. series, eds. G. Thomson and P. Sokolsk

Digital library access for illiterate users

The problems that illiteracy poses in accessing information are gaining attention from the research community. Issues currently being explored include developing an understanding of the barriers to information acquisition experienced by different groups of illiterate information seekers; creating technology, such as software interfaces, that support illiterate users effectively; and tailoring content to increase its accessibility. We have taken a formative evaluation approach to developing and evaluating a digital library interface for illiterate users. We discuss modifications to the Greenstone platform, describe user studies and outline resulting design implications

Collisions of low-energy electrons with isopropanol

We report measured and calculated cross sections for elastic scattering of low-energy electrons by isopropanol (propan-2-ol). The experimental data were obtained using the relative flow technique with helium as the standard gas and a thin aperture as the collimating target gas source, which permits use of this method without the restrictions imposed by the relative flow pressure conditions on helium and the unknown gas. The differential cross sections were measured at energies of 1.5, 2, 3, 5, 6, 8, 10, 15, 20, and 30 eV and for scattering angles from 10∘ to 130∘. The cross sections were computed over the same energy range employing the Schwinger multichannel method in the static-exchange plus polarization approximation. Agreement between theory and experiment is very good. The present data are compared with previously calculated and measured results for n-propanol, the other isomer of C_3H_7OH. Although the integral and momentum transfer cross sections for the isomers are very similar, the differential cross sections show a strong isomeric effect: In contrast to the f-wave behavior seen in scattering by n-propanol, d-wave behavior is observed in the cross sections of isopropanol. These results corroborate our previous observations in electron collisions with isomers of C_4H_9OH