Gas and Stellar Motions and Observational Signatures of Co-Rotating Spiral Arms

We have observed a snapshot of our N-body/Smoothed Particle Hydrodynamics simulation of a Milky Way-sized barred spiral galaxy in a similar way to how we can observe the Milky Way. The simulated galaxy shows a co-rotating spiral arm, i.e. the spiral arm rotates with the same speed as the circular speed. We observed the rotation and radial velocities of the gas and stars as a function of the distance from our assumed location of the observer at the three lines of sight on the disc plane, (l, b) = (90, 0), (120, 0) and (150,0) deg. We find that the stars tend to rotate slower (faster) behind (at the front of) the spiral arm and move outward (inward), because of the radial migration. However, because of their epicycle motion, we see a variation of rotation and radial velocities around the spiral arm. On the other hand, the cold gas component shows a clearer trend of rotating slower (faster) and moving outward (inward) behind (at the front of) the spiral arm, because of the radial migration. We have compared the results with the velocity of the maser sources from Reid et al. (2014), and find that the observational data show a similar trend in the rotation velocity around the expected position of the spiral arm at l = 120 deg. We also compared the distribution of the radial velocity from the local standard of the rest, V_LSR, with the APOGEE data at l = 90 deg as an example.Comment: 10 pages, 7 figures, accepted for publication in MNRA

The stellar kinematics of co-rotating spiral arms in Gaia mock observations

We have observed an N-body/Smoothed Particle Hydrodynamics simulation of a Milky Way like barred spiral galaxy. We present a simple method that samples N-body model particles into mock Gaia stellar observations and takes into account stellar populations, dust extinction and Gaia's science performance estimates. We examine the kinematics around a nearby spiral arm at a similar position to the Perseus arm at three lines of sight in the disc plane; (l,b)=(90,0), (120,0) and (150,0) degrees. We find that the structure of the peculiar kinematics around the co-rotating spiral arm, which is found in Kawata et al. (2014b), is still visible in the observational data expected to be produced by Gaia despite the dust extinction and expected observational errors of Gaia. These observable kinematic signatures will enable testing whether the Perseus arm of the Milky Way is similar to the co-rotating spiral arms commonly seen in N-body simulations.Comment: 9 pages 4 Figures, submitted to MNRAS 22nd Dec 201

Efficient Markets and Underwriting Performance in Small Stock Offerings

Robert J Angell is an Assitant Professor and Jerry G. Hunt is an Associate Professor in the Department of Accounting and Finance, School ot Business, East Carolina University, Greenville, North Carolina

NF04-594 Resistanct Management for YieldGard Rootworm™ \u3cem\u3eBt\u3c/em\u3e Corn

In 2003, the U.S. Environmental Protection Agency and Monsanto announced the registration of YieldGard Rootworm™ corn containing event MON863. These hybrids express a protein in the roots from the soil bacterium, Bacillus thuringiensis (Bt) that is toxic to larval corn rootworms. This NebFact discusses management requirements, refuge considerations, within-field configurations when using YieldGard Rootworm™

Impacts of a flaring star-forming disc and stellar radial mixing on the vertical metallicity gradient

Using idealized N-body simulations of a Milky Way-sized disc galaxy, we qualitatively study how the metallicity distributions of the thin disc star particles are modified by the formation of the bar and spiral arm structures. The thin disc in our numerical experiments initially has a tight negative radial metallicity gradient and a constant vertical scaleheight. We show that the radial mixing of stars drives a positive vertical metallicity gradient in the thin disc. On the other hand, if the initial thin disc is flared, with vertical scaleheight increasing with galactocentric radius, the metal-poor stars, originally in the outer disc, become dominant in regions above the disc plane at every radii. This process can drive a negative vertical metallicity gradient, which is consistent with the current observed trend. This model mimics a scenario where the star-forming thin disc was flared in the outer region at earlier epochs. Our numerical experiment with an initial flared disc predicts that the negative vertical metallicity gradient of the mono-age relatively young thin disc population should be steeper in the inner disc, and the radial metallicity gradient of the mono-age population should be shallower at greater heights above the disc plane. We also predict that the metallicity distribution function of mono-age young thin disc populations above the disc plane would be more positively skewed in the inner disc compared to the outer disc

Soybean Gall Midge in Nebraska

Soybean gall midge (Resseliella maxima Gagné) was described in 2019 as a new insect species in Nebraska, due to observations of widespread early season injury in eastern Nebraska, eastern South Dakota, western Iowa, and southwest Minnesota soybean fields (Gagné et al., 2019). Since its discovery, soybean gall midge has been causing significant injury and yield losses in soybean in eastern Nebraska. Although only recently identified, soybean gall midge is not likely new to the north- central region of the U.S. In 2011, orange larvae were documented in some isolated fields in northeast Nebraska that had received hail damage during the early half of the growing season. Similar reports were made in 2016 and 2017 in eastcentral Nebraska. Prior to 2018, reports of orange larvae in soybean were confined to the late reproductive stages of a few dead or dying plants. In 2018, several observations were made that raised concerns that soybean gall midge should be designated as a pest of soybean (McMechan et al. 2021). Unlike previous years where damaged plants were found later in the growing season, injured plants were observed in late June and early July. Soybean plants with larval presence exhibit signs of wilting and death, with the greatest frequency of symptomatic plants occurring along field borders adjacent to fields that had been planted to soybean the previous year. In many cases, the presence of dense vegetation (trees, uncut bromegrass, and/or shrubs) along field borders was associated with an increased frequency and intensity of plant injury. As a new species, several knowledge gaps must be bridged in order to development an integrated pest management strategy for soybean gall midge (McMechan et al. 2021) Year- to- year variability in the duration of emergence and injury from soybean gall midge has made it difficult to identify an effective control strategies. In 2018, soybean plants were hand- harvested from a heavily infested field in Saunders County, Nebraska, where a yield loss of 92%, was estimated for a section of the field in the first 100 feet from the field edge (compared to historical yields). Yield losses of 31% and 20% at 200 and 400 feet into the field, respectively, were also recorded (McMechan et al. 2021). Additional yield loss may also occur from early pod shatter from infested plants that mature ahead of the rest of the crop as well as lodging from weakened stems. As of 2020, soybean gall midge had been found in 114 counties in five states, with 39 counties infested in eastern Nebraska (Fig. 1). The distribution of soybean gall midge has increased each year since its discovery, although the extent of field injury is typically far less in newly identified counties

Radial Distribution of Stellar Motions in Gaia DR2

By taking advantage of the superb measurements of position and velocity for an unprecedented large number of stars provided in Gaia DR2, we have generated the first maps of the rotation velocity, $V_{\rm rot}$, and vertical velocity, $V_{\rm z}$, distributions as a function of the Galactocentric radius, $R_{\rm gal}$, across a radial range of $5<R_{\rm gal}<12$~kpc. In the $R-V_{\rm rot}$ map, we have identified many diagonal ridge features, which are compared with the location of the spiral arms and the expected outer Lindblad resonance of the Galactic bar. We have detected also radial wave-like oscillations of the peak of the vertical velocity distribution.Comment: 5 pages, 3 figures, accepted for publication in MNRAS Lette

Spiral and bar driven peculiar velocities in Milky Way sized galaxy simulations

We investigate the kinematic signatures induced by spiral and bar structure in a set of simulations of Milky Way-sized spiral disc galaxies. The set includes test particle simulations that follow a quasi-stationary density wave-like scenario with rigidly rotating spiral arms, and $N$-body simulations that host a bar and transient, co-rotating spiral arms. From a location similar to that of the Sun, we calculate the radial, tangential and line-of-sight peculiar velocity fields of a patch of the disc and quantify the fluctuations by computing the power spectrum from a two-dimensional Fourier transform. We find that the peculiar velocity power spectrum of the simulation with a bar and transient, co-rotating spiral arms fits very well to that of APOGEE red clump star data, while the quasi-stationary density wave spiral model without a bar does not. We determine that the power spectrum is sensitive to the number of spiral arms, spiral arm pitch angle and position with respect to the spiral arm. However, it is necessary to go beyond the line of sight velocity field in order to distinguish fully between the various spiral models with this method. We compute the power spectrum for different regions of the spiral discs, and discuss the application of this analysis technique to external galaxies.Comment: 14 pages, 11 figures. Improved and MNRAS Accepte

G80-521 Common Stalk Borer in Corn (Revised April 2000)

The life history and appearance of common stalk borers is described, along with information on damage they can cause, economic injury levels and ways to control them in corn. In the past, the common stalk borer, Papaipema nebris, has not been a major pest of corn in Nebraska. Stalk borer damage in corn commonly is confined to occasional plants in the first few rows near field margins, fence rows, grass terraces and waterways. In addition to attacking corn, this insect attacks over one hundred other species of plants, including ornamentals, broadleaf weeds and grasses. It may feed on soybeans as well, but is not an economically important pest of that crop. Understanding the common stalk borer life cycle and behavior is critical to selecting management practices to reduce its damage in corn