Ultrasonographic Evaluation of the Distal Extremity

Despite the increasing use of magnetic resonance imaging (MRI), ultrasound remains a valuable tool to diagnose injuries that cause distal extremity lameness in the horse. The key to a successful examination is a strong knowledge of anatomy in combination with proper ultrasonographic technique and the patience and dedication to learn these skills. Similar to all imaging modalities, it is equally important to recognize and consider the limitations of ultrasound in this region so that findings can be interpreted appropriately. Ultrasound can be used to diagnose injuries to the deep digital flexor tendon (DDFT), straight distal sesamoidean ligament and branches of the superficial digital flexor tendon using standard pastern ultrasonographic technique. The addition of newer techniques to image the DDFT at the level of P2, the navicular bursa and the collateral sesamoidean ligament can enhance the diagnostic utility of ultrasound in horses with distal extremity lameness. Although visibility is limited, ultrasound can be used to diagnose collateral ligament injuries of the coffin joint in many affected horses. Transcuneal imaging may be useful in some horses to detect abnormalities of the distal sesamoidean impar ligament and navicular bone, but evaluation of the DDFT is limited. Ultrasound should be considered in all horses with distal extremity lameness, regardless of the ability to perform advanced imaging procedures. Information gained is often complementary to other imaging modalities and may provide the basis for recheck examination purposes.     

Demographics of health and disease in the geriatric horse.

Owners of older horses have generally owned them for a long time. They have developed a bond that is similar to that seen with companion animals. Their desire to have their animal(s) age gracefully with comfort and mobility has stirred research in the field of equine geriatric medicine. Equine geriatric medicine is to the first decade of the twenty-first century as neonatal medicine was to the 1980s. Hopefully, the demographics discussed in this article highlight area where research can be most helpful.     

Economic Analysis of Composting Crab Processing Waste

A study of composting crab processing waste (CPW) was performed to identify a cost-effective alternative to landfilling. If CPW could be economically recycled into a useful value-added product, the waste would not have to go to landfills, and could be sold commercially to the landscaping and nursery industries. Economic models of three systems were constructed and analyses performed using a variety of investment and operating costs. To ensure robust model analysis, several factors of the cost components were varied. The equivalent-uniform-annual-costs were used to compare the alternatives, Ag-Bag, windrowing, and landfilling the waste. Profit analysis was also performed for each of the proposed systems. The average annual cost for the processes of Ag-Bag 1, Ag-Bag 2, and windrowing was $62,903, $73,796, and $53,533 respectively. While none of the methods analyzed were profitable, windrowing results in the smallest loss of $?0.066/kg ($?63.08/ton) for all economic models considered, followed by Ag-Bag 1 with an average loss of $?0.107/kg ($?100.18/ton) and Ag-Bag 2 with an average loss of $?0.117/kg ($?109.80/ton). Although having the least loss, windrowing has drawbacks such as offensive odors. A sensitivity analysis to determine how much additional throughput would have to be utilized to create a profit was performed. This analysis found that the windrow system is the only system capable of ever garnering a profit, with a total throughput exceeding 1,003 tons/year. Under current market conditions, composting CPW by one of the systems described herein is not feasible.     

Diurnal malate and citrate fluctuations as related to nitrate and potassium concentrations in tomato leaves

Abstract

Two experiments were conducted to determine if malate and citrate change diurnally, if these changes are light dependent, and how these changes relate to K⁺ and NO₃ ^?1 levels. Malate concentration in tomato leaves was shown to increase during the day and decrease at night. The inverse occurred with citrate. The dependency of the changes on light was demonstrated for malate, but not for citrate. A relationship with NO₃ ^? assimilation and K⁺ recirculation may explain the changes in malate concentration.     

Derivation of a Dynamic Model of the Kinetics of Nitrogen Uptake Throughout the Growth of Lettuce: Calibration and Validation

A kinetic model of nitrogen (N) uptake throughout growth was developed for lettuce cultivated in nutrient solution under varying natural light conditions. The model couples nitrogen uptake with dry matter accumulation using a two-compartment mechanistic approach, incorporating structural and non-structural pools. Maximum nitrogen uptake rates are assumed to decline with shoot dry weight, to allow for the effects of plant age. The model was parameterized using data from the literature, and calibrated for differences in light intensity using an optimization algorithm utilizing data from three experiments in different growing seasons. The calibrated model was validated against the data from two independent experiments conducted under different light conditions. Results showed that the model made good predictions of nitrogen uptake by plants from seedlings to maturity under fluctuating light levels in a glasshouse. Plants grown at a higher light intensity showed larger maximum nitrogen uptake rates, but the effect of light intensity declined towards plant maturity.     

Predation on Pacific herring (Clupea pallasi) spawn by birds in Prince William Sound,Alaska

We examined bird diets in areas with Pacific herring (Clupea pallasi) spawn at northern Montague Island in Prince William Sound, Alaska. Diets of the five most abundant bird species consisted primarily of herring spawn. Using a bioenergetics model, we estimated that in spring 1994 the five‐bird species ate 857.1 metric tons (mt), representing 31% of the estimated spawn deposition. The two most numerous consumers, glaucous‐winged gull (Larus glaucescens) and mew gull (Larus canus) consumed 26% and 3%, respectively, of the estimated spawn deposition. Surf scoters (Melanitta perspicillata), surfbirds (Aphriza virgata), and black turnstone (Arenaria melanocephala) together consumed 2% of the spawn deposition. In years with low spawn biomass, such as 1994, the number of herring larvae produced could be significantly affected by normal rates of avian predation. The high consumption by gulls, shorebirds, and surf scoters underscores the importance of herring spawn in the annual cycle of these species and requires further investigation.