The Public Face: Working the Front Desk of the UWC

A student’s first impression of the writing center is typically made at a reception desk. In the Undergraduate Writing Center (UWC) at the University of Texas at Austin, the front desk generally employs two staffers to welcome students, collect intake information, pair students with consultants, and do their best to ensure that consultations run smoothly. As a service that strives to provide a welcoming and supportive environment for students, the front desk's role is clearly important.University Writing Cente

Melilotus officinalis (Yellow Sweetclover) Causes Large Changes in Community and Ecosystem Processes in Both the Presence and Absence of a Cover Crop

Non-native species are hypothesized to decrease native species establishment and cover crops are hypothesized to decrease non-native species abundance. Although many studies have compared invaded to non-invaded habitats, relatively few studies have experimentally added non-native species to directly examine their effects. In a greenhouse mesocosm experiment, we tested the effects of non-native forbs (Melilotus officinalis, Verbascum thapsus, and Lespedeza cuneata), a proposed C3 grass cover crop (Pascopyrum smithii), and a commonly seeded non-native C3 grass (Bromus inermis) on the establishment of target native C4 prairie grass species. All treatments contained the same seed density of target C4 species and were begun on bare soil collected from the field. The legume M. officinalis strongly decreased the abundance of all other species, species diversity, and light and soil moisture levels. Surprisingly, M. officinalis took up relatively large amounts of labeled nitrogen (15N) from the soil early in its development, but M. officinalis fixed nitrogen, thus increasing nitrogen in biomass nearly fivefold by the end of the study. We found few effects of either C3 grass species on non-native forbs or C4 target species, but seeded P. smithii did increase species diversity. Non-native plants therefore impeded native C4 grass establishment through long-lasting effects of target species seedbank depletion (death of most target seedlings) and altered nutrient availability. The effects of M. officinalis were not reduced by the presence of a cover crop

Grassland Plant Composition Alters Vehicular Disturbance Effects in Kansas, USA

Many ‘‘natural’’ areas are exposed to military or recreational off-road vehicles. The interactive effects of different types of vehicular disturbance on vegetation have rarely been examined, and it has been proposed that some vegetation types are less susceptible to vehicular disturbance than others. At Fort Riley, Kansas, we experimentally tested how different plant community types changed after disturbance from an M1A1 Abrams tank driven at different speeds and turning angles during different seasons. The greatest vegetation change was observed because of driving in the spring in wet soils and the interaction of turning while driving fast (vegetation change was measured with Bray-Curtis dissimilarity). We found that less vegetation change occurred in communities with high amounts of native prairie vegetation than in communities with high amounts of introduced C3 grasses, which is the first experimental evidence we are aware of that suggests plant communities dominated by introduced C3 grasses changed more because of vehicular disturbance than communities dominated by native prairie grasses. We also found that vegetation changed linearly with vehicular disturbance intensity, suggesting that at least initially there was no catastrophic shift in vegetation beyond a certain disturbance intensity threshold. Overall, the intensity of vehicular disturbance appeared to play the greatest role in vegetation change, but the plant community type also played a strong role and this should be considered in land use planning. The reasons for greater vegetation change in introduced C3 grass dominated areas deserve further study

The Effect of Sexual Dichromatism on Subtle Gender Dimorphisms in Ecuadorian Hummingbirds

Within the birds there are countless examples of sexual dimorphism, ranging from obvious differences such as in plumage to more discreet variations such as in bill or wing length. The more conspicuous plumage differences are typically attributed to sexual selection, but the evolutionary cause of subtle dimorphisms is much more unclear, with sexual selection and ecological causation both being valid possibilities. Therefore the question arises, are subtle dimorphisms more correlated with species that are already sexually dichromatic, or do both plumage dimorphic and plumage monomorphic species have an equal likelihood of displaying discreet gender differences? To answer this we captured and analyzed fifteen different species of Ecuadorian hummingbirds, six of them being dichromatic, and nine of them being monochromatic. We measured four subtle traits in both genders across all species: weight, wing length, tail length, and culmen (bill) length, and used ANOVAs to determine if there were any significant differences between genders. Our results revealed that dichromatic species do have a greater chance of displaying subtle dimorphisms, with 83% of species having gender differences in at least one subtle trait as opposed to only 44% in monochromatic species. This indicates that there is a correlation between obvious gender differences like plumage and more discreet dimorphisms, although the cause for this, be it sexual selection of ecological causation, remains unclear. However, because some monochromatic species do display significant subtle dimorphisms, we have now opened the door to differentiating gender in these species in the absence of sexual structures

Relaxation Dynamics of Pseudomonas aeruginosa Re^I(C)O_3(α-diimine)(HisX)^+ (X=83, 107, 109, 124, 126)Cu-^(II) Azurins

Photoinduced relaxation processes of five structurally characterized Pseudomonas aeruginosa Re^I(CO)_3(α-diimine)(HisX) (X = 83, 107, 109, 124, 126)Cu^(II) azurins have been investigated by time-resolved (ps−ns) IR spectroscopy and emission spectroscopy. Crystal structures reveal the presence of Re-azurin dimers and trimers that in two cases (X = 107, 124) involve van der Waals interactions between interdigitated diimine aromatic rings. Time-dependent emission anisotropy measurements confirm that the proteins aggregate in mM solutions (D2O, KPi buffer, pD = 7.1). Excited-state DFT calculations show that extensive charge redistribution in the ReI(CO)_3 → diimine ^3MLCT state occurs: excitation of this ^3MLCT state triggers several relaxation processes in Re-azurins whose kinetics strongly depend on the location of the metallolabel on the protein surface. Relaxation is manifested by dynamic blue shifts of excited-state ν(CO) IR bands that occur with triexponential kinetics: intramolecular vibrational redistribution together with vibrational and solvent relaxation give rise to subps, 2, and 8−20 ps components, while the ~10^2 ps kinetics are attributed to displacement (reorientation) of the Re^I(CO)_3(phen)(im) unit relative to the peptide chain, which optimizes Coulombic interactions of the Re^I excited-state electron density with solvated peptide groups. Evidence also suggests that additional segmental movements of Re-bearing β-strands occur without perturbing the reaction field or interactions with the peptide. Our work demonstrates that time-resolved IR spectroscopy and emission anisotropy of Re^I carbonyl−diimine complexes are powerful probes of molecular dynamics at or around the surfaces of proteins and protein−protein interfacial regions

Yield and Production Costs for Three Potential Dedicated Energy Crops in Mississippi and Oklahoma Environments

The objective of this paper is to determine production costs of switchgrass, eastern gammagrass, and giant miscanthus using Mississippi and Oklahoma data. Production costs were computed using a standard enterprise budgeting approach by species and method of harvest. Results indicate cost difference across species and method of harvest.Yield and Cost, biomass species, Crop Production/Industries, Resource /Energy Economics and Policy,

The Effects of Roads on Movement, Flight Dynamics, Occupancy, and Productivity in Barn Owls (\u3cem\u3eTyto alba\u3c/em\u3e)

Barn Owls (Tyto alba) are a species of conservation concern in many portions of their cosmopolitan range. One important factor contributing to population declines and sometimes local extirpations is roads, which can cause direct mortality through Barn Owl-vehicle collisions, fragment habitat, limit dispersal and movement, and imperil long-term population viability. However, the effects of roads on Barn Owl reproduction are less clear. Further, the cumulative effects of roads on Barn Owls can be dependent on how they respond to them. Road and traffic responses of animals have been classified into four categories: 1) speeders, who increase speed to cross roads, 2) pausers, who pause before crossing, 3) avoiders, who avoid crossing roads altogether, and 4) nonresponders, who have no response to roads or traffic. Barn Owls, who are frequent victims of road mortality around the world and may even be attracted to the areas along roads for foraging, are hypothesized to be nonresponders. My goals were to examine Barn Owl behavior near roads to assess the extent to which they exhibited traits of nonresponders as well as to assess the possibility that they were attracted to areas near roads. Additionally, I aimed to examine the potential effects of roads on Barn Owl reproduction. To help understand Barn Owl behavior near roads I attached and recovered GPS data loggers from 19 Barn Owls to obtain location data on their movements. I first conducted a random walk analysis to assess how Barn Owl crossing rates and proximity to roads compared to what would be expected by chance. Additionally, I analyzed individual road encounters to help understand how flight dynamics affected their decision to cross a road and their behavior when actually crossing. I found that owls crossed fewer roads than expected, especially highways and interstates. Additionally, Barn Owls did not fly closer to roads than expected, including major roads and those of any size. When encountering roads, Barn Owls were more likely to cross when they approached at higher altitudes and when roads were narrower in width. When crossing roads, Barn Owls accelerated to cross when approaching at higher altitudes and slower speeds. They also decreased crossing altitude when approaching at higher altitudes and increased altitude to cross wider roads. These findings suggest that rather than being strict nonresponders, Barn Owls showed evidence of traits more associated with speeders and avoiders. To assess the potential effect of roads on Barn Owl reproduction I monitored a nest box population of Barn Owls between 2019 and 2022 to record breeding occupancy and productivity (number of fledglings) during two breeding seasons (2020 and 2021). I assessed occupancy in an average of 276 nest boxes per year and found that occupancy was 66%. Nests produced an average of 3.7 fledglings across the two breeding seasons (n = 225 nests). Both breeding occupancy and productivity decreased with proximity to roads. These results suggest that roads have the potential to influence owl populations not only through wildlife-vehicle collisions but indirectly through reductions in occupancy and productivity. Although it is alarming that roads are further impacting Barn Owls through their reproduction, my behavioral research suggests that rather than being strict nonresponders to roads, Barn Owls may avoid them to some degree, as well as reduce their risk of collision when crossing through changes in speed and altitude. Given the continuing expansion of road networks across the globe and the negative effects of roads on Barn Owl reproduction, it is encouraging that Barn Owls may be preadapted to the threat of roads, if not currently evolving adaptations in light of selective pressure, providing hope for the conservation of this species in a new and changing environment

Effects of Corn Crop Residue Grazing on Soil Physical Properties and Subsequent Soybean Production in a Corn–Soybean Crop Rotation

For three years beginning in 1999, a 96-acre field near Atlantic, Iowa was used to study the effects of corn residue grazing by beef cows on soil characteristics and soybean yields in subsequent years. Each winter, cows were allowed to graze corn crop residues inside selected paddocks in four sub-fields over five monthly periods. To compare the effects of grazing, one paddock was left as an ungrazed control. At the end of grazing in the spring, soil bulk density, moisture content, and penetration resistance were measured inside and 15 ft outside twelve grazing exclosures in each paddock. Soil surface roughness, texture, and type were also measured in twelve locations in each paddock. Corn crop residues were collected for yield, cover, and composition at the initiation, middle and termination of grazing. Precipitation and soil temperature also were recorded throughout the grazing season. Each following year, soybeans were planted in replicated subfields with disking or no tillage and harvested using a combine equipped with a yield monitor and global positioning system (GPS). Cattle grazing corn crop residue has shown no effect on soil bulk density, but there has been a measurable effect on penetration resistance in paddocks grazed in October and November (P\u3c 0.05). There is an increase in soil surface roughness during certain periods of cattle grazing where 75% of the variation can be contributed to increase in the amount of time soil temperature is above freezing. Cattle grazing had no effect on soybean plant population. However, 36 and 38% of the variation in soybean yield can be attributed to penetration resistance and soil surface roughness

Winter grazing of corn residues: Effects on soil properties and subsequent crop yields from a corn-soybean crop rotation

Corn residues could be a good resource for winter cattle grazing. The study investigates whether winter grazing causes soil compaction and yield reduction in crops that are planted following grazing

Effects of Corn Crop Residue Grazing on Soil Physical Properties and Subsequent Soybean Production in a Corn–Soybean Crop Rotation (A Progress Report)

Beginning in 1999, two locations in Iowa (Chariton, Atlantic) were used to study the effects of corn residue grazing by beef cows on soil characteristics and soybean yields the following growing season. Cows were allowed to graze inside selected paddocks at monthly periods throughout the fall and winter. For a grazed and ungrazed comparison, grazing exclosures were used inside the grazed paddocks, while one paddock was left ungrazed for a control. Also, the following year, equal portions of the fields went to no-tillage and disked soil prior to soybean planting so that effects of corn residue grazing on tillage treatments could be compared. The use of this design was to determine whether grazing had adverse effects on soil characteristics and, if so, at what date and weather conditions they occurred. Soil was analyzed for soil bulk density, moisture, penetration resistance, roughness, texture, and type. Corn crop residues were collected for yield, cover, and composition. Precipitation and soil temperature also were recorded throughout the grazing season. The following year, soybeans were harvested using a combine equipped with a yield monitor and global positioning system (GPS). After two years of study at both locations, some grazing fields with corn crop residue have shown effects on soil and crop residue characteristics. Organic matter (OM) yield of crop residue generally decreases at the faster rate in grazed fields than organic matter of ungrazed fields. However, corn crop residue composition was the same in grazed and ungrazed fields except for the 1999-2000 season at Chariton where crude protein decreased but acid detergent insoluble nitrogen (ADIN) increased with no difference in fiber content between grazed and ungrazed paddocks. Corn crop residue cover and soil roughness both can be greatly affected by the interaction of grazing and weather conditions. When the temperature is above freezing and precipitation is adequate, cattle traffic can cause roughness, while reducing residue cover by working it into the soil. Even though grazing corn residue by cattle can increase the surface roughness, it has not yet caused any increase in bulk density measurements or any reduction in soybean yields. Penetration resistance ratios have shown some significant difference between grazed and ungrazed paddocks, but the reason is unclear