Understanding and Optimizing Growth and Development of California Yellowtail (Seriola dorsalis) in Aquaculture Using Physiological Tools

Physical fitness metrics were used to assess the health and development of California Yellowtail, Seriola dorsalis, in an aquaculture environment during two grow-out experiments. The first experiment sought to evaluate the effects of a common aquaculture deformity (an improperly inflated swim bladder) that has been hypothesized to impact energy allocation, growth, and development. Metrics including metabolic rate, critical swimming speed, feed conversion ratio, and growth rate, were monitored over a 32-week period in three groups of California Yellowtail: wild-caught (“wild”), healthy hatchery-reared (“inflated”), and hatchery-reared with uninflated swim bladders (“uninflated”). At the start of the grow-out period, wild fish had a significantly lower standard metabolic rate (3.08 ± 0.23 mgO2 min-1 kg-1) than both the inflated and uninflated groups (5.60 ± 0.54 and 6.45 ± 0.66 mgO2 min-1 kg-1, respectively), but this difference was not maintained over time. After a 32-week growout, inflated fish had significantly greater mass (758.6 ± 92.7 g vs. 671.1 ± 128.9 g wild, 636.1 ± 80.4 g uninflated) and girth (23.2 ± 1.1 cm vs. 21.6 ± 1.7 cm wild, 21.5 ± 1.2 cm uninflated) than the other two groups, while uninflated fish had significantly shorter BL (36.5 ± 1.9 cm vs. 38.4 ± 2.7 cm wild, 39.6 ± 2.0 cm inflated). However, the wild fish had the most efficient feed conversion (1.41 vs. 1.49 inflated, 2.08 uninflated) and needed 5.8% less feed than the inflated group, and 47.8% less feed than the uninflated group to gain equivalent mass. In addition to indicating that it wouldn’t be economical to rear yellowtail with uninflated swim bladders due to their poor growth rates and feed conversion ratios, the results of this experiment revealed that there is room for improvement in the fitness of healthy aquaculture-reared yellowtail by potentially lowering their metabolic rate and feed conversion ratios. The subsequent experiment introduced exercise (which is typically lacking in aquaculture) as a means for improvement of fitness in hatchery-reared fish, and aimed to determine if a short duration of exercise could have lasting effects on the fitness of cultured yellowtail. Fish were forced to swim continuously against a flow in custom designed raceways for two, three, or four weeks, following which, metabolic rate, growth rate, and feed conversion were assessed over a 24-week grow-out period. Results showed that the duration of exercise may have an impact on standard metabolic rate immediately following exercise, with the exercised groups showing about a 9-15% reduction in metabolic rate. However, initial metabolic differences were not retained over time. Similarly, growth rates were stimulated by exercise, potentially because their lower standard metabolic rate reflected more efficient resource use and the ability to efficiently gain weight; however, the positive growth response also weakened with time. These results indicate that exercise could play an important role in the development of this species; however, the timing (e.g. yellowtail life stage and duration of exercise) and environmental variables (e.g. temperature and flow speed) likely play important roles in optimizing the response

Impaired Faculty: Helping Academics Who Are Suffering from Serious Mental Illness

Mental illness affects nearly every family. Recent epidemiological studies conducted by the World Health Organization (WHO) suggest over 26% of US citizens have a diagnosable mental illness at any one point in time (WHO World Mental Health Survey Consortium, 2004). In many cases, mental illness does not seriously impact functioning; individuals can still work, create, and teach, despite the presence of an illness. When mental illness intensifies, however, it can impact one’s ability to function in all domains of life, including the workplace. The same WHO survey suggested nearly 8% of Americans have a mental illness serious enough to interfere with completion of their normal activities more than one day a week (WHO World Mental Health Survey Consortium, 2004)

Solar Energy Conversion by Thermal Destruction of Conductivity

A method is proposed for converting solar radiation directly to electrical energy in space by utilizing the change of state of a superconductor. Apparatus is described whereby intermittent exposure to a concentrated beam of solar radiation causes a magnetic shield to fluctuate between the superconductive state (zero permeability) and the normal state (unity permeability) with resultant flux changes converted to electrical energy by conventional induction methods. A thermal embodiment of Lexis\u27s law, akin to the back torque of a conventional generator or the counter current in the primary of a transformer, is postulated. Such a reaction is demanded by energy conservation principles, although in the present case it can be exerted only against an input of purely thermal energy. In a heat engine working between heat quantities represented by intercepted solar flux at the upper limit and the black cold of space at the lower limit, a theoretical thermal efficiency in excess of 99% is possible. In order to realize this phenomenal efficiency in a heat engine with a radiator of practical size, a closed compound cycle is proposed in which a portion of the power output is used to drive a refrigerator. By compounding the cycle the net thermal efficiency is reduced but the effectiveness of the system remains unchanged, provided only that a part of the output of the converter be utilized in the cooling of other cryogenic devices such as superconductive delay lines, lasers, IR sensors etc., the balance being available for general purposes. The heat extracted from all cryogenic equipment, including the converter itself, can then be radiated away at a temperature high enough to benefit from the fourth power law. A practical form of the converter is described, with particular reference to the problem of eddy-current losses, which are unusually severe at very low temperatures