Serine-induced formation of aerial hyphae and conidia

Serine-induced formation of aerial hyphae and conidi

Anomalous \u3ci\u3eF\u3c/i\u3e Region Response to Moderate Solar Flares

Ionograms recorded with a dynasonde at Bear Lake Observatory, Utah, during moderate solar x-ray flares exhibit characteristic enhancements to the E and F 1 region ionosphere. However, during these same flares, the peak electron density of the ionosphere (N m F 2) unexpectedly decreases, recovering after the flare ends. In order to reconcile this anomalous behavior with expected increases to the total electron content (TEC), we undertake a modeling effort using the Time-Dependent Ionospheric Model (TDIM) developed at Utah State University. For solar input, a simple flare time irradiance model is created, using measurements from the Solar EUV Experiment instrument on the TIMED spacecraft. TDIM simulations show that the anomalous N m F 2 response can be explained by assuming a rapid electron temperature increase, which increases the O+ scale height, moving plasma to higher altitudes. The model results are able to reproduce both the decreasing N m F 2 as well as the expected TEC enhancement

Nitrogen placement, row spacing, and water management for furrow-irrigated field corn

Banding and sidedressing nitrogen (N) fertilizer on a never-irrigated side of a row of corn (Zea mays L.) were hypothesized to maintain yield and decrease nitrate leaching. In a two—year ?eld study on a Portneuf silt loam (Durinodic Xeric Haplocalcid) in southern Idaho, we evaluated effects on yield and N uptake of 1) urea placement (broadcast pre-plant vs. band at planting), 2) row spacings (30-in vs. an offset 22—in spacing in which every pair of 22-—in rows was positioned close to a furrow rather than each row on a bed center), and 3) water management. Our water management, termed irrigated furrow positioning, consisted of every- second furrow irrigation in which we applied water to either a) the same or b) the Opposite side of the row with successive irrigations, the latter called alternating furrow irrigation. At season’s end, we harvested 20 ft of row at three locations in each plot for silage and at three other locations for grain. Grain yield was not affected by the positioning of the irrigated furrow. However, averaged across years, grain yield from 22-in rows was 113 bu acre-1 from banded plots, 5% greater (P<0.05) than broadcast plots. Two-year average grain yield from 30-in rows was 107 bu acre-1, with no difference between banding and broadcasting. In the second year, N uptake in grain averaged across row spacings was 72.3 lb acre-l from banded plots and 65.5 lb acre-l from broadcast plots (P<0.01). Silage yield increased up to 26% and N uptake in silage increased up to 21% from banding, compared to broadcasting, where we irrigated the same furrow in the study’s second year. In both years, grain and silage yield and N uptake in grain and silage were similar or greater where urea was banded on one side of a row rather than broadcast

Nitrogen placement, row spacing, and water management for furrow-irrigated field corn

Banding and sidedressing nitrogen (N) fertilizer on a never-irrigated side of a row of corn (Zea mays L.) were hypothesized to maintain yield and decrease nitrate leaching. In a two—year ?eld study on a Portneuf silt loam (Durinodic Xeric Haplocalcid) in southern Idaho, we evaluated effects on yield and N uptake of 1) urea placement (broadcast pre-plant vs. band at planting), 2) row spacings (30-in vs. an offset 22—in spacing in which every pair of 22-—in rows was positioned close to a furrow rather than each row on a bed center), and 3) water management. Our water management, termed irrigated furrow positioning, consisted of every- second furrow irrigation in which we applied water to either a) the same or b) the Opposite side of the row with successive irrigations, the latter called alternating furrow irrigation. At season’s end, we harvested 20 ft of row at three locations in each plot for silage and at three other locations for grain. Grain yield was not affected by the positioning of the irrigated furrow. However, averaged across years, grain yield from 22-in rows was 113 bu acre-1 from banded plots, 5% greater (P<0.05) than broadcast plots. Two-year average grain yield from 30-in rows was 107 bu acre-1, with no difference between banding and broadcasting. In the second year, N uptake in grain averaged across row spacings was 72.3 lb acre-l from banded plots and 65.5 lb acre-l from broadcast plots (P<0.01). Silage yield increased up to 26% and N uptake in silage increased up to 21% from banding, compared to broadcasting, where we irrigated the same furrow in the study’s second year. In both years, grain and silage yield and N uptake in grain and silage were similar or greater where urea was banded on one side of a row rather than broadcast

Refilling of Geosynchronous Flux Tubes as Observed at the Equator by GEOS 2

During periods of extended quiet geomagnetic activity the geosynchronous satellite orbit lies inside the plasmasphere. Five such periods were observed by the GEOS 2 satellite. During the initial 48 hours of such periods the equatorial plasma flux tube density increases at 30 to 50 cm−3/day. However, on reaching ∼100 cm−3 the refilling rate decreases, and refilling is limited. Only when the density reaches ∼100 cm−3 do the plasma characteristics and fluctuations appear to be plasmaspheric and the flow predominantly corotational. The “hot outer zone” of the plasmasphere is highly structured in density and temperature when viewed from a corotating satellite. This region also has a relatively dense population of warm subkilovolt electrons. These warm electrons whose density is ∼1% to 50% of the cold plasma may be the heat source for the hot outer zone ions

Validation Study of the Ionospheric Forecast Model Using the TOPEX TEC Measurements

As a part of the validation program in the Utah State University Global Assimilation of Ionospheric Measurement (GAIM) project, a newly improved Ionosphere Forecast Model (IFM) was systematically validated by using a large database of TOPEX total electron content (TEC) measurements. The TOPEX data used for the validation are for the period from August 1992 to March 2003, and the total number of 18-s averaged data is close to 11 million. This model validation work covers a wide range of seasonal (winter, summer, and equinox) and solar (low-F 10.7, median F 10.7, and high-F 10.7) conditions as well as all UT variations with the focus on nonstorm time TEC. The validation results indicate that the features of the spatial distribution of the IFM TEC are systematically consistent with those of the TOPEX TEC. The differences between the IFM TEC and the TOPEX TEC are within 20% for almost all locations and conditions. For many conditions, the differences are even below 10%

The Flow of Plasma in the Solar-Terrestrial Environment

The overall goal of our NASA theory research is to trace the flow of mass, momentum, and energy through the magnetosphere-ionosphere-atmosphere system taking into account the coupling, time delays, and feedback mechanisms that are characteristic of the system. Our approach is to model the magnetosphere-ionosphere-atmosphere (M-I-A) system in a self-consistent quantitative manner using unique global models that allow us to study the coupling between the different regions on a range of spatial and temporal scales. The uniqueness of our global models stems from their high spatial and temporal resolutions, the physical processes included, and the numerical techniques employed. Currently, we have time-dependent global models of the ionosphere, thermosphere, polar wind, plasmasphere, and electrodynamics. It is now becoming clear that a significant fraction of the flow of mass, momentum, and energy in the M-I-A system occurs on relatively small spatial scales. Therefore, an important aspect of our NASA Theory program concerns the effect that mesoscale (100-l000 km) density structures have on the macroscopic flows in the ionosphere, thermosphere, and polar wind. The structures can be created either by structured magnetospheric inputs (i.e., structured electric field, precipitation, or Birkeland current patterns) or by time variations of these inputs due to geomagnetic storms and substorms. Some of the mesoscale structures of interest include sun-aligned polar cap arcs, propagating plasma patches, traveling convection vortices, subauroral ion drift (SAID) channels, gravity waves, and the polar hole

Polar Topside Ionosphere During Geomagnetic Storms: Comparison of ISIS-II With TDIM

Space weather deposits energy into the high polar latitudes, primarily via Joule heating that is associated with the Poynting flux electromagnetic energy flow between the magnetosphere and ionosphere. One way to observe this energy flow is to look at the ionospheric electron density profile (EDP), especially that of the topside. The altitude location of the ionospheric peak provides additional information on the net field‐aligned vertical transport at high latitudes. To date, there have been few studies in which physics‐based ionospheric model storm simulations have been compared with topside EDPs. A rich database of high‐latitude topside ionograms obtained from polar orbiting satellites of the International Satellites for Ionospheric Studies (ISIS) program exists but has not been utilized in comparisons with physics‐based models. Of specific importance is that the Alouette/ISIS topside EDPs spanned the timeframe from 1962 to 1983, a period that experienced very large geomagnetic storms. We use a physics‐based ionospheric model, the Utah State University Time Dependent Ionospheric Model (TDIM), to simulate ionospheric EDPs for quiet and storm high‐latitude passes of ISIS‐II for two geomagnetic storms. This initial study finds that under quiet conditions there is good agreement between model and observations. During disturbed conditions, however, a large difference is seen between model and observations. The model limitation is probably associated with the inability of its topside boundary to replicate strong outflow conditions. As a result, modeling of the ionospheric outflows needs to be extended well into the magnetosphere, thereby moving the upper boundary much higher and requiring the use of polar wind models

Life Beyond the Solar System: Space Weather and Its Impact on Habitable Worlds

The search of life in the Universe is a fundamental problem of astrobiology and a major priority for NASA. A key area of major progress since the NASA Astrobiology Strategy 2015 (NAS15) has been a shift from the exoplanet discovery phase to a phase of characterization and modeling of the physics and chemistry of exoplanetary atmospheres, and the development of observational strategies for the search for life in the Universe by combining expertise from four NASA science disciplines including heliophysics, astrophysics, planetary science and Earth science. The NASA Nexus for Exoplanetary System Science (NExSS) has provided an efficient environment for such interdisciplinary studies. Solar flares, coronal mass ejections and solar energetic particles produce disturbances in interplanetary space collectively referred to as space weather, which interacts with the Earth upper atmosphere and causes dramatic impact on space and ground-based technological systems. Exoplanets within close in habitable zones around M dwarfs and other active stars are exposed to extreme ionizing radiation fluxes, thus making exoplanetary space weather (ESW) effects a crucial factor of habitability. In this paper, we describe the recent developments and provide recommendations in this interdisciplinary effort with the focus on the impacts of ESW on habitability, and the prospects for future progress in searching for signs of life in the Universe as the outcome of the NExSS workshop held in Nov 29 - Dec 2, 2016, New Orleans, LA. This is one of five Life Beyond the Solar System white papers submitted by NExSS to the National Academy of Sciences in support of the Astrobiology Science Strategy for the Search for Life in the Universe.Comment: 5 pages, the white paper was submitted to the National Academy of Sciences in support of the Astrobiology Science Strategy for the Search for Life in the Univers