Output Of Mass Research Articles

Delaying panicle nitrogen application to emergence of 3rd leaf from flag leaf increases the grain-filling ability and yield of large-panicle rice by increasing stem nonstructural carbohydrates at heading

The reserve of stem nonstructural carbohydrates (NSC) at heading can enhance the sink strength and improve the grain-filling ability of large-panicle rice, which is beneficial to realizing its high-yield potential. Delaying panicle nitrogen (N) application is expected to increase stem NSC accumulation, but the relevant technical parameters and their impact on the yield of large-panicle rice remain unclear. Two-year field experiments were conducted in 2021 and 2022 with two large-panicle rice cultivars (HLY280 and YLY228) and five panicle N treatments: panicle N application at emergence of 4th leaf from flag leaf (TL4), 3rd leaf from flag leaf (TL3), 2nd leaf from flag leaf (TL2), flag leaf (TL1), and no panicle N application (CK) as the control, to study the effect of different panicle N treatments on the accumulation and translocation of stem NSC, as well as their impact on rice yield and its components. The results showed that the panicle N treatments significantly influenced rice yield. Among the panicle N application treatments, TL3 showed the highest yield for both cultivars over two years. Compared with TL4, TL3 significantly increased the percentage of filled grains and grain weight while maintaining a similar number of spikelets per panicle, which increased the yield of HLY280 and YLY228 by 10.1–13.6% and 12.4–12.7%, respectively. Among the panicle N application treatments, TL3 significantly increased the translocation of stem mass (net output of stem mass) and stem NSC (∆NSC) from heading to 15 days after heading (DAH), which led to the highest dry matter accumulation during the initiation of grain filling from heading to 15 DAH. The higher ∆NSC of TL3 was mainly due to the higher stem NSC at heading, which was contributed by the higher stem NSC accumulation from 5 days before heading (DBH) to heading. Additionally, the higher stem NSC accumulation under TL3 from 5 DBH to heading was significantly positively correlated with the higher leaf area duration (LAD) in this period. These results suggest that delaying panicle N application to TL3 can significantly increase the yield of large-panicle rice compared with TL4 by increasing the percentage of filled grains and grain weight, which is the result of increased stem NSC accumulation.

Coupled chemical reactions: Effects of electric field, diffusion, and boundary control.

Chemical reactions involve the movement of charges, and this paper presents a mathematical model for describing chemical reactions in electrolytes. The model is developed using an energy variational method that aligns with classical thermodynamics principles. It encompasses both electrostatics and chemical reactions within consistently defined energetic and dissipative functionals. Furthermore, the energy variation method is extended to account for open systems that involve the input and output of charge and mass. Such open systems have the capability to convert one form of input energy into another form of output energy. In particular, a two-domain model is developed to study a reaction system with self-regulation and internal switching, which plays a vital role in the electron transport chain of mitochondria responsible for ATP generation-a crucial process for sustaining life. Simulations are conducted to explore the influence of electric potential on reaction rates and switching dynamics within the two-domain system. It shows that the electric potential inhibits the oxidation reaction while accelerating the reduction reaction.

Агроэкологическое испытание люцерны в условиях Сахалина

Field studies were conducted in 2021–2022 at the experimental site of the Sakhalin Research Institute of Agriculture on meadow-sod-gley medium loamy soil according to generally accepted methods. The technology of cultivation of alfalfa is in accordance with the methods of cultivation of perennial herbs developed by the Sakhalin Research Institute of Agriculture. The scheme of the experiment included ten varieties of alfalfa of various ecological and geographical origin. The greatest foliage was demonstrated by plants of the varieties Uralochka, Victoria, Nakhodka in the first mowing and the varieties Uralochka, Vela, Nakhodka, Sarga in the second. The varieties that entered the top three in terms of green mass yield for the period of the first mowing were Taisiya, Sarga and Uralochka varieties. As for the output of the dry mass it was similar. According to the amount of green and dry mass formed in the second mowing the varieties Nakhodka, Taisiya and Sarga were distinguished as the best. On average, for two mowing of the green mass the leading varieties were distributed in such order: the 1st place — the Taisiya variety, the 2nd place — Sarga and Nakhodka, the 3rd third place – Victoria, Agnia VIK and Uralochka. The average yield of the green mass of the Vela variety for two mowing was inferior to the standard Demetra variety by 8%, the yield of the Voronezhskaya 6 variety was at the standard level, the other varieties exceeded the standard by 7.4–21.2%. The average yield of the dry mass for two mowing of the Pavlovskaya 7 variety was slightly inferior to the standard variety, the Vela and Voronezh 6 varieties it was at the standard level, the rest exceeded it by 11.6–35.6%.

A New Perspective on Regulation of Pituitary Plasticity: The Network of SOX2-Positive Cells May Coordinate Responses to Challenge.

Plasticity of function is required for each of the anterior pituitary endocrine axes to support alterations in the demand for hormone with physiological status and in response to environmental challenge. This plasticity is mediated at the pituitary level by a change in functional cell mass resulting from a combination of alteration in the proportion of responding cells, the amount of hormone secreted from each cell, and the total number of cells within an endocrine cell population. The functional cell mass also depends on its organization into structural and functional networks. The mechanisms underlying alteration in gland output depend on the strength of the stimulus and are axis dependent but in all cases rely on sensing of output of the functional cell mass and its regulation. Here, we present evidence that the size of pituitary cell populations is constrained and suggest this is mediated by a form of quorum sensing. We propose that pituitary cell quorum sensing is mediated by interactions between the networks of endocrine cells and hormone-negative SOX2-positive (SOX2+ve) cells and speculate that the latter act as both a sentinel and actuator of cell number. Evidence for a role of the network of SOX2+ve cells in directly regulating secretion from multiple endocrine cell networks suggests that it also regulates other aspects of the endocrine cell functional mass. A decision-making role of SOX2+ve cells would allow precise coordination of pituitary axes, essential for their appropriate response to physiological status and challenge, as well as prioritization of axis modification.

Building a mathematical model of technological processes in the acetic acid synthesis reactor

The result of the study reported in this paper is the proposed mathematical model of technological processes occurring in the reactor for acetic acid synthesis. The initial parameters of the reactor considered were the value of the concentration of acetic acid at the reactor outlet, temperature, the level of reaction mass, and pressure in the reactor. The input parameters included the amount of methanol and carbon monoxide supplied. Material and thermal balances of reactor technological processes were used to construct the mathematical model of the reactor. Fisher criterion was applied to test the mathematical model for adequacy. At the specified 5 % level of significance, the value of Fisher criterion for the concentration of acetic acid, temperature, and the level of reaction mass in the reactor does not exceed its critical value for a stationary mode. The reproducibility of the modeling results was tested using the Cochran criterion. The value of the Cochrane criterion, at the predefined 5 % level of significance, for the concentration of acetic acid, temperature, and the level of reaction mass in the reactor does not exceed its critical value for different modes. The relative error for the modeled output parameters was calculated. The relative error of the initial parameters did not exceed the level of 10 %. The model built makes it possible to calculate with satisfactory accuracy the value of the concentration of acetic acid at the reactor output, the temperature and level of the reaction mass in the reactor under a stationary mode. The resulting model could be used to automate the control of technological processes in the acetic acid synthesis reactor under a stationary mode. The study results open additional opportunities to manage the stationary mode of the reactor

ЭФФЕКТИВНОСТЬ И ФИЗИОЛОГИЧЕСКАЯ БЕЗОПАСНОСТЬ ГОРОХА В РАЦИОНАХ КУР-НЕСУШЕК (Gallus gallus L.) РОДИТЕЛЬСКОГО СТАДА НА ПОЗДНИХ СРОКАХ СОДЕРЖАНИЯ

Feeds are accounted for ca. 70 % of the commercial production costs of eggs and poultry meat. The use of other legumes (lupine, peas, horse beans, vetch) can lower the feed costs. However, the antinutritive factors of the legumes should be taken into account in the receipt formulation, especially in diets for pedigree flocks. Earlier we have proven physiological safety and effectiveness of the inclusion of 15 % of lupine in diets for layer parental flock. The substitution of peas for soybeans and lupine as the dietary protein source can further lower the costs of finisher diets for broilers and post-peak diets for layers where reduced protein levels are required. In the study presented we found efficient the substitution of peas (5 and 10 %) for soybean meal and sunflower cake in diets for parental flock of cage-housed layer chicken (cross SP 78, 30 birds per treatment) at the end of prolonged productive period (54-71 weeks of age). Control treatment 1 was fed the complete mash compound feed with soybeans as protein source; in diets for treatments 2, 3, and 4 the soybeans were increasingly substituted by peas (5, 10, and 15 % of total diet, respectively). After the artificial insemination 100 eggs from each treatment was taken since 70 weeks of age and incubated in DANKI incubator (Belgium) in constant regime. The temperature was set at 37.7 °Ð¡ during 1-18 days of incubation and 37.2 °Ð¡ during 18-21 days and controlled with the accuracy 0.1 °Ð¡; the relative humidity during these periods was 52-53 and 52-75 %, respectively. Mortality level, egg production, feed conversion ratios (per 10 eggs and per 1 kg of eggs laid), egg fertility and hatchability were recorded. The concentrations of vitamins and caroteniods in liver, chemical composition of liver, tibial concentrations of calcium and phosphorus were determined according to standard methods. The effects of the antinutritive factors were assessed via the histological study of the liver (at 71 weeks of age, <em>n</em> = 12); the samples were taken in 1 hour after the euthanasia from the similar liver part (lateral side of the right lobe) and fixed in 10 % neutral aqueous formalin. It was found that the inclusion of 5 and 10 % of peas into the diets of parental layer flock increased the intensity of lay by 2.38 and 4.97 % in compare to control, respectively, output of egg mass per hen housed by 3.78 and 12.23 %; the percentage of infertile eggs in these treatments was lower in compare to control. The histological study of liver revealed that 15 % of peas can launch the cytotoxic effect on the hepatic structures and induce the hepatic steatosis. This effect should be taken into account in the receipt formulations. It could be also concluded that peas can be included into the diets without preliminary thermal treatment; the antinutritive effects of pectin, trypsin inhibitors and proteases, tannins could be alleviated via the additional supplementation of the diets with exogenous enzymes, organic acids, and hepatoprotective agents.

PRODUCTIVITY OF NEW MAIZE HYBRIDS IN CONDITIONS OF THE URALS

The research aimed to identify the most productive hybrids selected by the All-Russian Research Institute of Maize to cultivate by the cereal seed technology in the natural conditions of the Middle Cis- Urals. Methodology. Maize was cultivated for seeds and green fodder for farm animals in the conditions of the Middle Cis-Urals. The maize green mass, consisting mainly of stems and leaves, usually contains up to 88-90% water. Silage being prepared for it has less dry matter and protein. Such fodder has low nutritional value and poor return from livestock products. The most high quality and nutritious feed can be received from maize seeds or its above-ground mass with seeds of milky-wax and wax ripeness. To select early-maturing hybrids with high nutritional value is the primary concern for the studied area. Results. The results demonstrate that the productivity of maize hybrids ranges from 2.50 to 6.76 t/ha depending on soil and climatic conditions. When maize hybrids are grown by seed technology, the above-ground mass of the studied crops is 30.68-68.80 t/ha. Conclusions. It is necessary to select earlier ripening and highly productive hybrids to increase the quality and nutrition of corn feed. The recommended hybrids for grain production are Ural 150 (5,45 t/ha), Baikal (5,38 t/ha) and Mashuk 170 MV (4,98 t/ha); K-170 (56,7 t/ha), Shihan (55,67 t/ha) and Mashuk 170 MV (54,99 t/ha) that provided a higher output of the green mass at milky-wax ripeness of grain are best for silage production. The resulting data make it possible to select maize hybrids with high yields and nutritional value for farms with similar soil and climate conditions and to develop diets for highly productive dairy and beef cattle.

The Ability to Dissipate Heat Is Likely to Be a More Important Limitation on Lactation in Striped Hamsters with Greater Reproductive Efforts under Warmer Conditions

The limitations on energy availability and outputs have been implied to have a profound effect on the evolution of many morphological and behavioral traits. It has been suggested that the reproductive performance of mammals is frequently constrained by intrinsic physiological factors, such as the capacity of the mammary glands to produce milk (the peripheral limitation [PL] hypothesis) or that of the body to dissipate heat (the heat dissipation limitation [HDL] hypothesis). Research on a variety of small mammals, however, has so far failed to provide unequivocal support for one hypothesis over the other. We tested the PL and HDL hypotheses in female striped hamsters (Cricetulus barabensis) with artificially manipulated litter sizes of two (three or four pups removed from natural litter size), five, eight (two or three pups added to natural litter size), and 12 (five to seven pups added to natural litter size) pups at ambient temperatures of 21° and 30°C. Energy intake and milk output of mothers, litter size, and litter mass were measured throughout lactation. Several markers indicating digestive enzyme activity and the gene expression of hypothalamic neuropeptides related to food intake were also measured. Food consumption and milk output increased with increasing litter size but reached a ceiling at 12 pups, causing 12-pup litters to have significantly lower litter mass and pup body mass than litters composed of fewer pups. Litter mass and maternal metabolic rate, milk output, maltase, sucrase, and aminopeptidase activity in the small intestine, and gene expression of hypothalamic orexigenic peptides were significantly lower at 30°C than at 21°C, and these differences were considerably more pronounced in 12-pup litters. These results suggest that PL and HDL can operate simultaneously but that the HDL hypothesis is probably more valid at warmer temperatures. Our results suggest that increased environmental temperatures in future climates may limit reproductive output through heat dissipation limits.

СРАВНИТЕЛЬНАЯ ОЦЕНКА ИНДЕЕК РАЗНЫХ КРОССОВ И ПОРОДНЫХ ГРУПП ПО ПРОДУКТИВНЫМ КАЧЕСТВАМ

In recent years, special importance has been attached to turkey breeding as one of the most effective poultry industries, supplying the most valuable meat of all species of birds. For the production of turkey meat is used heavy, medium and light crosses turkeys of different breeds, including new - Hybreed. The aim of the work was to compare the qualities of turkeys of different crosses of white broad-chested and hybrid birds Hybreed. In hybrid birds Hybreed in the breed heavy cross on live weight in all periods exceeds the average cross of 670 grams or 1.31 times in 4 weeks, 1040 grams or 27.4% and then 61.4-70.6% (P < 0.01, P < 0.001), in periods hybrid bird Hybreed and its crosses have a higher genetic potential of productivity, have high rates of growth and its intensity, which allows before slaughter in 120 and 150 days, depending on the cross to have turkeys with a high live weight of 10,83-23,20 kg, respectively.The advantage of the output of muscle mass and the edible part of the carcass remains for a hybrid bird Hybrid. This applies to both medium and heavy crosses of this breed group. They were superior to turkeys of white broad-chested breed by pre-slaughter weight and weight of chilled carcass on the average cross by 2.53 and 2.51 kg, respectively, or by 23.4-28.6%; by heavy cross by 10.9 and 8.55 kg or 47.0%. The profitability of turkey meat production, depending on the cross and breed (breed group) ranges from 58.8% (group 2, heavy cross, white broad-breasted turkey) to 193.2% (group 4, heavy cross, Hybreed highbrid birds).

Oscillation modes of vibrating feeders with vibro-impact adaptive drive at the output of reflacted ore from chambers of wining blocks

The oscillation modes of vibrating feeders with vibro-impact adaptive drive are researched, which are intended for output and loading of reflacted ore from chambers of wining blocks at underground mining, or other bulk media from bunkers and so on, under complicated vibration conditions. The resonant polyfrequency oscillations of the impactor of the vibro-impact drive of feeders with such drive in vibro-impact modes are excited, which through one-side elastic elements are transmitted to the feeder tray, and in the pillar of the reflacted ore in the chamber above the tray. With increasing load from the ore on the tray there is an increase in the intensity of the impactor vibration of the feeder vibro-impact drive with accelerations in hundreds m/s2. Such oscillations increase the depth of dissemination of vibrational effects in a pillar of reflacted ore above the tray, which increases the efficiency and productivity of vibration output. Depending on the feeders parameters in its oscillatory system, various modes of vibro-impact oscillations are excited. The task of choosing the mode of variation of the feeder is to choose such parameters, which would ensure efficient vibration output of the rock mass and reliability of its operation.

STUDY OF THE DIFFERENT WAYS OF PROTEINS EXTRACTION FROM SHEEP AND COW WHEY FOR “URDA” CHEESE PRODUCTION

The necessary stage of technological process of “Urda” albumin cheese production is whey proteins extraction from sheep whey (in classic technology of product) or from the whey mixtures, offered in the work. For whey proteins extraction from whey the following ways are used: thermal, acid, acid-alkaline and chlorine-calcium. There was established the equal dependence of the influence of the way of proteins extraction from both sheep and cow whey on the output of protein mass. The most output of protein mass (3,47±0,10 %) is at the chlorine-calcium way of proteins extraction, a bit less – 3,41±0,08 % – at the acid-alkaline way. But the acidity of such protein mass, received by the chlorine-calcium and acid-alkaline ways is not high – 37,2±1,8 and 45,6±1,4 % respectively that negatively influences the gustatory qualities of product. The least output is registered at the thermal way. Albumin cheese, received from such protein mass, was the best by its gustatory qualities. The output of protein mass from sheep whey is 1,60 times higher than from cow whey. The mass share of proteins in protein mass, received from sheep whey is by 6,9…8,0 % higher comparing with one, received from cow whey. Protein mass, received from sheep whey by the chlorine-calcium and acid-alkaline ways has the low titrated acidity. Cheese, received from protein mass, received of sheep whey by the acid method, has the extremely high acidity values (115,5±1,5 °Т), excessive sour-milk flavor and smell. These results don-t allow to provide the long storage term. That is why it is recommended to use the thermal way for proteins extraction from sheep whey and for proteins extraction from cow way in the technology of “Urda” albumin cheese. So the thermal way of proteins extraction from the mixture of sheep and cow whey in ratio 1:1 or 3:1 can be used for “Urda” albumin cheese production. The use of cow whey gives a possibility to cheapen the product because cow whey is cheaper than sheep one. Such cheese has the improved organoleptic parameters, namely homogenous consistence, tender sour-milk flavor and smell.

Numerical simulation of hydrodynamics and heat transfer in the technological reservoir with the heat pump

The mathematical modeling of mixed convection of viscous incompressible fluid in a rectangular reservoir with the sources of input and output of mass has been carried out. Is studied the influence of heat sink as a result of the work of heat pump and its position on the formation of convective flows and a change in the temperature conditions. Are revealed basic laws governing the heat transfer in the small environment of heat pump. The analysis of the influence of Reynolds numbers on the intensity of the heat exchange is carried out.

Generalization of the Landau submerged jet solution

We consider a class of exact solutions of the hydrodynamic equations generalizing the Landau submerged jet solution. The obtained solutions do not vanish with the disappearance of viscosity and describe nonzero output or nonzero absorption of fluid mass from the respective sources or sinks located on one axis.

EXERGY ANALYSIS OF PRE-COOLED LINDE SYSTEM FOR LIQUEFACTION OF GASES FOR IMPROVING PERFORMANCE OF LINDE BASED CRYOGENICS SYSTEMS

Cryogenic temperature generally temperature below the -150 o C .Various number of gases are liquefy by using very first Linde Hampson cycle but due to inefficiency of system output of liquefaction mass is very low as compared to expanses. Linde Pre-cooled system is designed to meet the gap in the basic Linde system. The output as well as the second law efficiency of Linde pre-cooled system is more than the basic Linde system. A complete thermo –analysis of pre-cooled Linde system is carried out and various results are predicted. The effect of some various parameters like refrigerant mass flow ratio and compressor pressure on system with six different gases is studied by applying computational numerical technique. Effect of these parameters on system conclude that the system work good near 200 bar pressure and refrigerant mass flow ratio of 0.03 is suitable for system showing high second law efficiency and Liquefaction mass ratio and low work done per liquefaction mass ratio.

Reflux Drying of Aerosols

The goal of our efforts has been to generate high aerosolized drug concentrations, so that the entire inhaled dose may be delivered to the animal in a relatively short time interval, typically one minute or less. In this report, we have examined the use of a reflux condenser coupled with an external heat source as a means to dry aerosol particles. The specific interest was to examine the parameters influencing the drying process and identify practical experimental conditions that would allow drying of aerosol particles. Aqueous solutions of cesium chloride were atomized with an ultrasonic driver, and the resulting cloud was subsequently passed through an externally heated column with an inner condenser cooled with flowing water. Increasing the airflow rate increased the output of total mass(water + CsCl) but decreased the particle transit efficiency. At a constant airflow rate, decreasing the wall-to-condenser temperature ratio led to a progressive increase in particle loss, but a maximum was observed in the water removal efficiency. While thermal diffusion and the thermophoretic effect may have an impact on the drying process, non-steady state conditions, convective currents, inertial impaction, turbulence, and changes in the condenser boundary layer are likely to have a role in particle drying. In spite of the numerous complexities, practical operating conditions were identified for efficient particle drying with high dry mass transit efficiency.

Sustainable, high-yielding outdoor mass cultures of Chaetoceros muelleri var. subsalsum and Isochrysis galbana in vertical plate reactors.

Continuous cultures of Chaetoceros muelleri and Isochrysis galbana were grown outdoors in flat plate-glass reactors in which light-path length (LPL) varied from 5 to 30 cm. High daily productivity (13 to 16 g cell mass per square meter of irradiated reactor surface) for long periods of time was obtained in reactors in which the optical path as well as cell density were optimized. 'Twenty centimeters was the optimal LPL, yielding the highest areal productivity of cell mass (g m(-2)d(-1)), eicosapentaenoic acid, and docosahexaenoic acid, which was identical with that previously found for polysaccharide production of Porphyridium and not far from the optimal LPL affecting maximal productivity in Nannochloropsis species. Relating the energy impinging on a given reactor surface area to the appropriate number of cells showed that the most efficient light dose per cell, obtained with the 20-cm LPL reactor, was approximately 2.5 times lower than the light dose available per cell in the 5-cm LPL reactor, in which a significant decline in areal cell density accompanied the lowest areal output of cell mass. The most effective harvesting regimen was in the range of 10% to 15% of culture volume harvested daily and replaced with fresh growth medium, resulting in a sustainable culture density of 24 x 10(6) and 28 x 10(6) cells/ml of C. muelleri and I. galbana, respectively.

Evaluation of morphological and functional regeneration of rat nerve-muscle units after temporary and permanent tubulization.

We compared the ability of temporary and permanent tubing to achieve morphological and functional recovery of nerve-muscle units, following experimental nerve transection (8-mm gap) in rat tibial nerve. Electrical stimulation of the sciatic nerve was used to analyze tension output, evoked electromyogram and conduction-transmission time (CTT) of denervated nerve-muscle units. Morphological analysis of the nerve and muscle was also performed. Within 6 weeks, the nerve gap had been bridged by a thin nerve trunk, and a few myelinated fibers were observed, although there was still no functional recovery. The rats were divided into two groups: permanent tubing (PT) and temporary tubing (TT; tubing subsequently removed). At 10 weeks after the operation, the TT group showed apparently greater thickness of regenerated nerve trunks, significantly higher tension output of plantar flexors, shorter CTT, and heavier muscle mass. These results were consistent with the presence of myelinated fibers in the regenerated nerve trunks, as shown histologically. Thus, removal of the silicone chamber results in faster and better recovery than tubing left permanently in place.

Three selected ecological observations interpreted in terms of a thermodynamic hypothesis. Contribution to a general theoretical framework

Biology and ecology are, in many ways, lacking universal laws and predictive theory, and most biologists and ecologists have been feeling the need for a more general and integrative theoretical network that may help in explaining their observations and experimental results. Thermodynamics has been widely applied in ecosystem theory since input, output, and cycling of mass and energy constitute the basis of ecological processes without exception. In this paper, we try to show that it is possible to explain different empirical biological and ecological observations in terms of a comprehensive thermodynamic hypothesis, instead of interpreting results according to a number of non-universal generalisations (e.g. the optimal partition theory or the ‘generalised niche model’). The intention is to contribute to the elaboration of a general theoretical framework in biology and ecology, of which the thermodynamic hypothesis could be a part. The proposed approach is shown to be robust enough to provide an integrated explanation for the selected set of observations, and the fact that it was able to explain field observations and experiments supports the hypothesis. A stepwise approach is employed in developing a consistent theoretical framework, considered necessary to build new horizons for biology and ecology.

An industrial-size flat plate glass reactor for mass production of Nannochloropsis sp. (Eustigmatophyceae)

A flat plate (10 cm light-path), vertical reactor made of 10-mm glass plates glued together to form a 500- to 1000-l unit was developed for outdoor production of Nannochloropsis sp., one of the most promising photoautotrophic producer of eicosapentaenoic acid (20:5ω3, EPA) for aquaculture. The energy inputs required for mixing and cooling the culture were calculated and the harvesting regime yielding the highest areal output of cell mass and EPA was identified. The reactor is practically sealed, facilitating successful maintenance of continuous, monoalgal cultures throughout the year. The optimal cell density fell in the range of 5 to 6×10 8 cells ml −1, a high cell concentration compared with that reported for other mass production systems of Nannochloropsis. This population density yielded in continuous cultures throughout the year an average of 12 g dry cell mass m −2 day −1 or 650 mg EPA m −2 day −1, on the basis of the entire illuminated reactor area. An economic appraisal is provided for operating a 2000-l reactor, sufficient to supply all the algal mass for production of the rotifer quantity required by a Seabream hatchery producing 8×10 6 fingerlings annually. The production cost at this rather modest scale shows strong sensitivity to the cost of labor.

Why do tuna maintain elevated slow muscle temperatures? Power output of muscle isolated from endothermic and ectothermic fish.

It has been hypothesised that regional endothermy has evolved in the muscle of some tunas to enhance the locomotory performance of the fish by increasing muscle power output. Using the work loop technique, we have determined the relationship between cycle frequency and power output, over a range of temperatures, in isolated bundles of slow muscle fibres from the endothermic yellowfin tuna (Thunnus albacares) and its ectothermic relative the bonito (Sarda chiliensis). Power output in all preparations was highly temperature-dependent. A counter-current heat exchanger which could maintain a 10 degrees C temperature differential would typically double maximum muscle power output and the frequency at which maximum power is generated (fopt). The deep slow muscle of the tuna was able to operate at higher temperatures than slow muscle from the bonito, but was more sensitive to temperature change than more superficially located slow fibres from both tuna and bonito. This suggests that it has undergone some evolutionary specialisation for operation at higher, but relatively stable, temperatures. fopt of slow muscle was higher than the tailbeat frequency of undisturbed cruising tuna and, together with the high intrinsic power output of the slow muscle mass, suggests that cruising fish have a substantial slow muscle power reserve. This reserve should be sufficient to power significantly higher sustainable swimming speeds, presumably at lower energetic cost than if intrinsically less efficient fast fibres were recruited.