3,663 research outputs found
Aircrew-aircraft integration: A summary of US Army research programs and plans
A review of selected programs which illustrate the research efforts of the U.S. Army Aeromechanics Laboratory in the area of aircrew-aircraft integration is presented. Plans for research programs to support the development of future military rotorcraft are also described. The crew of a combat helicopter must, in general, perform two major functions during the conduct of a particular mission: flightpath control and mission management. Accordingly, the research programs described are being conducted in the same two major categories: (1) flightpath control, which encompasses the areas of handling qualities, stability and control, and displays for the pilot's control of the rotorcraft's flightpath, and (2) mission management, which includes human factors and cockpit integration research topics related to performance of navigation, communication, and aircraft systems management tasks
A review of US Army aircrew-aircraft integration research programs
If the U.S. Army's desire to develop a one crew version of the Light Helicopter Family (LHX) helicopter is to be realized, both flightpath management and mission management will have to be performed by one crew. Flightpath management, the helicopter pilot, and the handling qualities of the helicopter were discussed. In addition, mission management, the helicopter pilot, and pilot control/display interface were considered. Aircrew-aircraft integration plans and programs were reviewed
Promote Growth and Animal Health with Isoflavones in Red Clover and Other Legumes
The field of nutrition has continued to expand since the 18th century. We once thought that the only important components in foods and feeds were proteins, carbohydrates, fats and salts. Evidence was slowly pieced together to show that certain minor components were essential for life, and the vitamins were discovered. Like the doctors that first suspected vitamins were essential, some cattlemen have long noted advantages in animal performance and health on certain diets in ways that cannot be explained by a simple forage analysis. Today, we are learning the roles that phenolic plant secondary metabolites, sometimes called polyphenols, play in both human and animal nutrition. In particular, our USDA-ARS unit is conducting research on a group of polyphenols called isoflavones, which are found in clovers and other legumes.
Isoflavones prevent damage by ultraviolet light in plants. They are also a chemical defense against infection by bacteria and fungi. It has long been recognized that isoflavones also have biological effects on animals that consume the plants. They are antioxidants and estrogens. The estrogenic effects of legumes, well known in ruminants, are due to isoflavones. Much of the early research on isoflavones in ruminant diets is about their negative effects on reproduction. However, new research is showing there are benefits to cattle that consume isoflavones. In this article, we will explore two recently discovered benefits of isoflavones: 1) improved dietary nitrogen efficiency, and 2) improved blood flow during fescue toxicosis
Removal of terrestrial DOC in aquatic ecosystems of a temperate river network
Surface waters play a potentially important role in the global carbon balance. Dissolved organic carbon (DOC) fluxes are a major transfer of terrestrial carbon to river systems, and the fate of DOC in aquatic systems is poorly constrained. We used a unique combination of spatially distributed sampling of three DOC fractions throughout a river network and modeling to quantify the net removal of terrestrial DOC during a summer base flow period. We found that aquatic reactivity of terrestrial DOC leading to net loss is low, closer to conservative chloride than to reactive nitrogen. Net removal occurred mainly from the hydrophobic organic acid fraction, while hydrophilic and transphilic acids showed no net change, indicating that partitioning of bulk DOC into different fractions is critical for understanding terrestrial DOC removal. These findings suggest that river systems may have only a modest ability to alter the amounts of terrestrial DOC delivered to coastal zones
Characterization of Grazing Patterns in Cool-Season Annual and Warm-Season Perennial Grass Pastures
Pastures are often either under- or over-grazed, which can affect both pasture sustainability and livestock performance. Disk meter heights were measured for rye (Secale cereale L.) -ryegrass (Lolium L. multiflorum Lam.) pasture to characterize stocking rate (2.5, 3.7, and 4.9 steers/ha) effects on grazing patterns. In another study, grazing indices were calculated for bermudagrass [Cynodon dactylon (L.) Pers.] to describe pasture utilization over time for three stocking rates (3.0, 5.9, 8.9 steers/ha). Distributions of DMH for rye-ryegrass showed distinct grazing patterns for each stocking rate, with the distributions changing from bimodal to multi-modal from heavy to light stocking rates. Bermudagrass was not pattern grazed, but grazing indices showed that the extent that pastures were grazed was not consistent over time for any of the stocking rates
Dimensions of Internet Commerce Trust
Trust is a central construct and plays a critical role in understanding Internet consumer behavior. This research seeks to directly address the subject of Internet Commerce Trust (ICT) by developing a valid, reliable, and generalizable scale to measure this multifaceted subject. Two separate studies reveal a common five-factor structure. These dimensions are labeled (1) Certification, (2) Resources and Capabilities, (3) Shopping Method, (4) Reliability, and (5) Communication Viability. An accurate measurement of ICT will serve as a viable control factor in future studies of Internet consumer behaviors, segmentation analyses, and in marketing strategy research
Forage-Animal Production Research Unit (FAPRU): Establishment of a New USDA-ARS Research Location
Forages are vital to the success of grazing livestock production systems. Forages provide a low cost source of nutrients for animal production (Barnes & Nelson 2003; Ball et al., 1996). Limited fundamental (i.e., genomic, proteomic, metabolomic) research on the effects of environment and management on plant quality and production and the effects of plant metabolites (i.e., nutrients, anti-quality factors, nutraceuticals) on animal performance has hindered our ability to improve the productivity of forage-based enterprises. There is insufficient information for reliable prediction of animal performance in response to plant metabolites. To address these issues, USDA-ARS established FAPRU (Forage-Animal Production Research Unit) in 2003 at U Kentucky, Lexington. Its mission is to improve the productivity, profitability, competitiveness and sustainability of forage-based enterprises through improved understanding of the fundamental biological processes that occur at the animal-plant interface
Potential for Use of a Perennial C3 Grass in a Warm-Temperate Region with Pastures Dominated by C4 Grasses
Tall fescue is a perennial cool-season forage grass utilized over an extensive area of the USA; however, adaptation is limited across the Coastal Plain region of the southeastern states including Louisiana. Stands of the original variety, Kentucky 31, from early plantings either failed to persist or were replaced as adverse effects on grazing livestock by an ergot alkaloid toxin from an association of tall fescue with an endophytic fungus were recognized. Management approaches can moderate the adverse effects allowing productive use of existing tall fescue pastures. Endophyte removal from tall fescue allowed development of useful cultivars for the primary tall fescue growing area, but these endophyte-free cultivars proved to be less persistent in marginal areas such as Louisiana. Recently available varieties with novel, nontoxin-producing endophytes have shown potential in northern Louisiana with stand persistence for 4 years on some sites. Cool-season perennial grass pastures can be realistic components of forage systems in areas such as northern Louisiana. Existing remnant stands can be beneficial with appropriate management, and, as indicated by ongoing research, new novel-endophyte varieties may prove useful on selected sites
Effect of Biochanin A on the Rumen Microbial Community of Holstein Steers Consuming a High Fiber Diet and Subjected to a Subacute Acidosis Challenge
Subacute rumen acidosis (SARA) occurs when highly fermentable carbohydrates are introduced into the diet, decreasing pH and disturbing the microbial ecology of the rumen. Rumen amylolytic bacteria rapidly catabolize starch, fermentation acids accumulate in the rumen and reduce environmental pH. Historically, antibiotics (e.g., monensin, MON) have been used in the prevention and treatment of SARA. Biochanin A (BCA), an isoflavone produced by red clover (Trifolium pratense), mitigates changes associated with starch fermentation ex vivo. The objective of the study was to determine the effect of BCA on amylolytic bacteria and rumen pH during a SARA challenge. Twelve rumen fistulated steers were assigned to 1 of 4 treatments: HF CON (high fiber control), SARA CON, MON (200 mg d-1), or BCA (6 g d-1). The basal diet consisted of corn silage and dried distiller’s grains ad libitum. The study consisted of a 2-wk adaptation, a 1-wk HF period, and an 8-d SARA challenge (d 1–4: 40% corn; d 5–8: 70% cracked corn). Samples for pH and enumeration were taken on the last day of each period (4 h). Amylolytic, cellulolytic, and amino acid/peptide-fermenting bacteria (APB) were enumerated. Enumeration data were normalized by log transformation and data were analyzed by repeated measures ANOVA using the MIXED procedure of SAS. The SARA challenge increased total amylolytics and APB, but decreased pH, cellulolytics, and in situ DMD of hay (P \u3c 0.05). BCA treatment counteracted the pH, microbiological, and fermentative changes associated with SARA challenge (P \u3c 0.05). Similar results were also observed with MON (P \u3c 0.05). These results indicate that BCA may be an effective alternative to antibiotics for mitigating SARA in cattle production systems
Exogenous Lactobacilli Mitigate Microbial Changes Associated with Grain Fermentation (Corn, Oats, and Wheat) by Equine Fecal Microflora \u3cem\u3eEx Vivo\u3c/em\u3e
Cereal grains are often included in equine diets. When starch intake exceeds foregut digestion starch will reach the hindgut, impacting microbial ecology. Probiotics (e.g., lactobacilli) are reported to mitigate GI dysbioses in other species. This study was conducted to determine the effect of exogenous lactobacilli on pH and the growth of amylolytic and lactate-utilizing bacteria. Feces were collected from 3 mature geldings fed grass hay with access to pasture. Fecal microbes were harvested by differential centrifugation, washed, and re-suspended in anaerobic media containing ground corn, wheat, or oats at 1.6% (w/v) starch and one of five treatments: Control (substrate only), L. acidophilus, L. buchneri, L. reuteri, or an equal mixture of all three (107 cells/mL, final concentration). After 24 h of incubation (37°C, 160 rpm), samples were collected for pH and enumerations of total amylolytics, Group D Gram-positive cocci (GPC; Enterococci, Streptococci), lactobacilli, and lactate-utilizing bacteria. Enumeration data were log transformed prior to ANOVA (SAS, v. 9.3). Lactobacilli inhibited pH decline in corn and wheat fermentations (P \u3c 0.0001). Specifically, addition of either L. reuteri or L. acidophilus was most effective at mitigating pH decline with both corn and wheat fermentation, in which the greatest acidification occurred (P \u3c 0.05). Exogenous lactobacilli decreased amylolytics, while increasing lactate-utilizers in corn and wheat fermentations (P \u3c 0.0001). In oat fermentations, L. acidophilus and L. reuteri inhibited pH decline and increased lactate-utilizers while decreasing amylolytics (P \u3c 0.0001). For all substrates, L. reuteri additions (regardless of viability) had the lowest number of GPC and the highest number of lactobacilli and lactate-utilizers (P \u3c 0.05). There were no additive effects when lactobacilli were mixed. Exogenous lactobacilli decreased the initial (first 8 h) rate of starch catalysis when wheat was the substrate, but did not decrease total (24 h) starch utilization in any case. These results indicate that exogenous lactobacilli can impact the microbial community and pH of cereal grain fermentations by equine fecal microflora ex vivo. Additionally, dead (autoclaved) exogenous lactobacilli had similar effects as live lactobacilli on fermentation. This latter result indicates that the mechanism by which lactobacilli impact other amylolytic bacteria is not simple resource competition
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