Persistence of Tall Fescue and Cattle Grazing Preference as Affected by Endophyte Status

Endophyte-infected (E+) grasses often exhibit increased survival, growth and resistance to herbivory compared to uninfected counterparts. Latch (1997) proposed a strategy for cultivar improvement of infecting elite cultivars with strains of Neotyphodium coenophialum that are non-toxic to livestock, but still able to convey the persistence advantage shown with wild-type, toxic endophyte. The strategy of re-infecting tall fescue (Lolium arundinaceum (Schreb.) Darbysh.) cultivars with naturally occurring, non-ergot-producing endophytes appears promising for removing animal toxicity symptoms and retaining agronomic performance (Bouton et al., 2002; Hill et al., 2002). The objective of this study was to compare the effect of endophyte status on grazing preference and persistence of tall fescue stand

Estimating total horizontal aeolian flux within shrub-invaded groundwater-dependent meadows using empirical and mechanistic models

Wind erosion is a significant environmental problem that removes soil resources from sensitive ecosystems and contributes to air pollution. In regions of shallow groundwater, friable (puffy) soils are maintained through capillary action, surface evaporation of solute-rich soil moisture, and protection from mobilization by groundwater-dependent grasses and shrubs. When a reduction in vegetation cover occurs through any disturbance process, there is potential for aeolian transport and dust emission. We find that as mean gap size between vegetation elements scaled by vegetation height increases, total horizontal aeolian sediment flux increases and explains 58% of the variation in total horizontal aeolian sediment flux. We also test a probabilistic model of wind erosion based on gap size between vegetation elements scaled by vegetation height (the Okin model), which predicts measured total horizontal aeolian sediment flux more closely than another commonly used model based on the average plant area observed in profile (Raupach model). The threshold shear velocity of bare soil appears to increase as gap size between vegetation elements scaled by vegetation height increases, reflecting either surface armoring or reduced interaction between the groundwater capillary zone and surface sediments. This work advances understanding of the importance of measuring gap size between vegetation elements scaled by vegetation height for empirically estimating Q and for structuring process-based models of desert wind erosion in groundwater-dependent vegetation

Ungulate preference for burned patches reveals strength of fire–grazing interaction

The interactions between fire and grazing are widespread throughout fire-dependent landscapes. The utilization of burned areas by grazing animals establishes the fire–grazing interaction, but the preference for recently burned areas relative to other influences (water, topography, etc.) is unknown. In this study, we determine the strength of the fire–grazing interaction by quantifying the influence of fire on ungulate site selection. We compare the preference for recently burned patches relative to the influence of other environmental factors that contribute to site selection; compare that preference between native and introduced ungulates; test relationships between area burned and herbivore preference; and determine forage quality and quantity as mechanisms of site selection. We used two large ungulate species at two grassland locations within the southern Great Plains, USA. At each location, spatially distinct patches were burned within larger areas through time, allowing animals to select among burned and unburned areas. Using fine scale ungulate location data, we estimated resource selection functions to examine environmental factors in site selection. Ungulates preferred recently burned areas and avoided areas with greater time since fire, regardless of the size of landscape, herbivore species, or proportion of area burned. Forage quality was inversely related to time since fire, while forage quantity was positively related. We show that fire is an important component of large ungulate behavior with a strong influence on site selection that drives the fire–grazing interaction. This interaction is an ecosystem process that supersedes fire and grazing as separate factors, shaping grassland landscapes. Inclusion of the fire–grazing interaction into ecological studies and conservation practices of fire-prone systems will aid in better understanding and managing these systems

Coherence loss and revivals in atomic interferometry: A quantum-recoil analysis

The coherence effects induced by external photons coupled to matter waves inside a Mach-Zehnder three-grating interferometer are analyzed. Alternatively to atom-photon entanglement scenarios, the model considered here only relies on the atomic wave function and the momentum shift induced in it by the photon scattering events. A functional dependence is thus found between the observables, namely the fringe visibility and the phase shift, and the transversal momentum transfer distribution. A good quantitative agreement is found when comparing the results obtained from our model with the experimental data.Comment: 18 pages, 4 figure

Normothermia is protective during infrarenal aortic surgery

AbstractPurpose: Mild hypothermia has been suggested to be protective against tissue ischemia during aortic operations. However, recent studies have documented detrimental cardiac effects of hypothermia during a variety of operative procedures. The influence of different warming methods and the impact of hypothermia during standard aortic procedures was assessed. Methods: One hundred patients who underwent repair of infrarenal aortic aneurysms or aortoiliac occlusive disease were prospectively randomized into 2 groups, receiving either a circulating water mattress or a forced air warming blanket. Adjuvant warming methods were standardized. The day before surgery, 48-hour Holter monitors were applied and interpreted by a cardiologist blinded to the treatment. Randomization resulted in equivalent groups with regard to patient history, indications for surgery, body mass index, length of surgery, and fluid requirements. Results: Core temperatures were significantly warmer during surgery (36.3°C ± 0.7°C vs 35.4 ± 0.8°C) and after surgery (36.4°C ± 0.7°C vs 35.6°C ± 0.9°C) in patients with forced air warming (P < .001). The circulating water mattress group had significantly more metabolic acidosis perioperatively (P = .03). Postoperative length of stay, cardiac complications, and death rates were not significantly different. Subgroup analysis of 83 aneurysm patients comparing normothermia with hypothermia (temperature less than 36°C) on arrival to the recovery room identified decreased cardiac output (P = .02), thrombocytopenia (P = .02), elevated prothrombin time (P = .04), and inferior Acute Physiology and Chronic Health Evaluation (APACHE) II scores (P < .001) in the hypothermic group. Holter analysis revealed more sinus tachycardia (ST) segment changes and ventricular tachycardia in hypothermic aneurysm patients (P = .05). Conclusion: Patients treated with forced air blankets had significantly less metabolic acidosis and were kept significantly warmer than those treated with circulating water mattresses. Patients with aneurysms that were kept normothermic had a significantly improved clinical profile, with fewer cardiac events on the Holter recordings. We therefore conclude that (1) normothermia is protective for infrarenal aortic surgical patients; and (2) forced air warming blankets provide improved temperature maintenance compared with circulating water mattresses. (J Vasc Surg 1998;28:984-94.

Inhibition of inducible nitric oxide synthase limits nitric oxide production and experimental aneurysm expansion

AbstractPurpose: Nitric oxide (NO), frequently cited for its protective role, can also generate toxic metabolites known to degrade elastin. Both abdominal aortic aneurysms (AAAs) and inducible nitric oxide synthase (iNOS) are associated with inflammatory states, yet the relationship between NO production by iNOS and AAA development is unknown. The current study examines iNOS expression, NO production, and the effects of selective inhibition of iNOS by aminoguanidine in experimental AAA. Methods: An intra-aortic elastase infusion model was used. Control rats received intra-aortic saline infusion and postoperative intraperitoneal saline injections (Group 1). In the remaining groups, intra-aortic elastase infusion was used to induce aneurysm formation. These rats were treated with intraperitoneal injections of saline postoperatively (Group 2), aminoguanidine postoperatively (Group 3), or aminoguanidine preoperatively and postoperatively (Group 4). Aortic diameter and plasma nitrite/nitrate levels were measured on the day of surgery and postoperative day 7. Aortas were harvested for biochemical and histologic analysis on postoperative day 7. Results: Infusion of elastase produced AAAs (P <.001) with significant production of iNOS (P <.05) and nitrite/nitrate (P <.003) compared with controls. Selective inhibition of iNOS with aminoguanidine in elastase-infused aortas significantly reduced aneurysm size (P <.01) compared with elastase infusion alone. Aminoguanidine-treated rats displayed suppression of iNOS expression and plasma nitrite/nitrate production not significantly different from the control group. Histologic evaluation revealed equivalent inflammatory infiltrates in elastase-infused groups. Conclusion: Expression of iNOS is induced and plasma nitrite/nitrate levels are increased in experimental AAA. Inhibition of iNOS limits NO production and iNOS expression, resulting in smaller aneurysm size. NO production by iNOS plays an important role with detrimental effects during experimental aneurysm development. (J Vasc Surg 2001;33:579-86.

Al-26 production profile and model comparisons in Canyon Diablo

The large preatmospheric size of the Canyon Diablo meteorite, a radius of about 15 m, makes it especially suitable for systematic studies of cosmogenic nuclide production rates of iron objects in a 2 pi geometry. To reconstruct the exposure history of the meteoroid, Heymann et al. investigated several fragments recovered from known geographic locations around the crater for their shock features and cosmogenic nobel gases. They applied the Signer-Nier noble gas production rate model to establish the preatmospheric depth of the specimens in the meteoroid. Cosmic ray exposure ages suggested a multi-episodic irradiation, with 170 or 540 Ma being inferred for most of the samples studied while two anomalous specimens indicated a possible third exposure age at 940 Ma. Be-10 and Cl-36 have been measured in a number of these same samples by accelerator mass spectrometry (AMS), with use being made of the preatmospheric depths determined in Heymann et al. to construct production profiles. The present study extends the cosmogenic radionuclide data to Al-26 and compares the results with both the production rate model of Reedy and Arnold and production rates determined from the cross sections used by the Reedy-Arnold model (for the major nuclear reactions making Al-26) in combination with differential fluxes calculated using the Los Alamos High Energy Transport (LAHET) Code System. Model calculations for Be-10 and Cl-36 have also been obtained

Testing the Effects of Two Field-to-Fork Programs on the Nutritional Outcomes of Elementary School Students from Diverse and Lower-income Communities

The purpose of this quasi-experimental study was to evaluate the effects of two farm-to-school programs, specifically the Field-to-Fork Multi-visit Program (N  =  264) and the Field-to-Fork After-school Club (N  =  56), on nutritional outcomes of elementary school students (third to fifth grade) from urban, diverse, and lower-income communities. Data were collected via self-report surveys measuring: (a) knowledge of recommendations for daily fruit and vegetable intake; (b) fruit and vegetable consumption; (c) knowledge of cooking a healthy recipe using vegetables; and (d) desire for farm fresh foods at school. Statistical analyses included McNemar’s and Wilcoxon signed rank tests. The proportion of students knowing how to cook a vegetable rich recipe increased with both programs (Multi-visit Program p \u3c .001; After-school Club p  =  .002). Vegetable consumption increased with the After-school Club (p  =  .002). Farm-to-school programming can increase knowledge of cooking vegetable rich recipes and vegetable intake among elementary school students from diverse, urban, and lower-income communities

Clean option: Berkeley Pit water treatment and resource recovery strategy

The US Department of Energy (DOE), Office of Technology Development, established the Resource Recovery Project (RRP) in 1992 as a five-year effort to evaluate and demonstrate multiple technologies for recovering water, metals, and other industrial resources from contaminated surface and groundwater. Natural water resources located throughout the DOE complex and the and western states have been rendered unusable because of contamination from heavy metals. The Berkeley Pit, a large, inactive, open pit copper mine located in Butte, Montana, along with its associated groundwater system, has been selected by the RRP for use as a feedstock for a test bed facility located there. The test bed facility provides the infrastructure needed to evaluate promising technologies at the pilot plant scale. Data obtained from testing these technologies was used to assess their applicability for similar mine drainage water applications throughout the western states and at DOE. The objective of the Clean Option project is to develop strategies that provides a comprehensive and integrated approach to resource recovery using the Berkeley Pit water as a feedstock. The strategies not only consider the immediate problem of resource recovery from the contaminated water, but also manage the subsequent treatment of all resulting process streams. The strategies also employ the philosophy of waste minimization to optimize reduction of the waste volume requiring disposal, and the recovery and reuse of processing materials