RESUMEN

Gaseous NH3 removal was studied in laboratory-scale biofilters (14-L reactor volume) containing perlite inoculated with a nitrifying enrichment culture. These biofilters received 6 L/min of airflow with inlet NH3 concentrations of 20 or 50 ppm, and removed more than 99.99% of the NH3 for the period of operation (101, 102 days). Comparison between an active reactor and an autoclaved control indicated that NH3 removal resulted from nitrification directly, as well as from enhanced absorption resulting from acidity produced by nitrification. Spatial distribution studies (20 ppm only) after 8 days of operation showed that nearly 95% of the NH3 could be accounted for in the lower 25% of the biofilter matrix, proximate to the port of entry. Periodic analysis of the biofilter material (20 and 50 ppm) showed accumulation of the nitrification product NO3- early in the operation, but later both NO2- and NO3- accumulated. Additionally, the N-mass balance accountability dropped from near 100% early in the experiments to approximately 95 and 75% for the 20- and 50-ppm biofilters, respectively. A partial contributing factor to this drop in mass balance accountability was the production of NO and N2O, which were detected in the biofilter exhaust.

Asunto(s)

RESUMEN

The development of the sequential structure of dustbathing bouts was studied in domestic egg-layer chicks from hatching until 23 days of age using a first order Markov chain model analysis. Chicks were reared either with access to sand ("sand chicks ") or on a wire floor ( "wire chicks"). All chicks in both groups developed a basic structure of the elements pecking, bill raking, ground scratching, vertical wingshaking, head rubbing, and side rubbing. Nonetheless, there was more cohesion in the bouts of sand chicks than in those of wire chicks: wire chicks had more pauses in their bouts and performed more elements while standing; also, allopecking (feather-pecking) and preening were incorporated into their bouts. We conclude that the basic structure of dustbathing bouts develops even in the absence of functional experience with feedback from sand. However, absence of normal feedback can lead to problems consisting of interruptions and feather-directed behavior.

Asunto(s)

RESUMEN

Whereas Earth-based composting reactors that effectively control the process are batch operations with bottom-to-top airflow, in extraterrestrial application both the fresh waste and the air need to be introduced from above. Stabilized compost and used air would exit below. This materials flow pattern permits the addition of waste whenever generated, obviating the need for multiple reactors, and the incorporation of a commode in the lid. Top loading in turn dictates top-down aeration, so that the most actively decomposing material (greatest need for heat removal and O2 replenishment) is first encountered. This novel material and aeration pattern was tested in conjunction with temperature feedback process control. Reactor characteristics were: working, volume, 0.15 m3; charge, 2 kg dry biomass per day (comparable to a 3-4 person self-sufficient bioregenerative habitat); retention time, 7 days. Judging from temperature profile, O2 level, air usage, pressure head loss, moisture, and odor, the system was effectively controlled over a 35-day period. Dry matter disappearance averaged 25% (10-42%). The compost product was substantially, though not completely, stabilized. This demonstrates the compatibility of top-wise introduction of waste and air with temperature feedback process control.

Asunto(s)

RESUMEN

As a candidate technology for treating solid wastes and recovering resources in bioregenerative Advanced Life Support, composting potentially offers such advantages as compactness, low mass, near ambient reactor temperatures and pressures, reliability, flexibility, simplicity, and forgiveness of operational error or neglect. Importantly, the interactions among the physical, chemical, and biological factors that govern composting system behavior are well understood. This article comparatively evaluates five Generic Systems that describe the basic alternatives to composting facility design and control. These are: 1) passive aeration; 2) passive aeration abetted by mechanical agitation; 3) forced aeration--O2 feedback control; 4) forced aeration--temperature feedback control; 5) forced aeration--integrated O2 and temperature feedback control. Each of the five has a distinctive pattern of behavior and process performance characteristics. Only Systems 4 and 5 are judged to be viable candidates for ALS on alien worlds, though which is better suited in this application is yet to be determined.

Asunto(s)

RESUMEN

Behavior systems are particular organizations of cognitive structures that are called behavior mechanisms: perceptual, central, and motor. Thus, behavior systems are defined here in structural terms and not in terms of their functional characteristics. In young animals, behavior mechanisms often develop independently of functional experience, though specific types of experience are usually necessary for integrated systems to develop. These concepts are illustrated here by the dust-bathing, feeding, aggressive, and sexual systems of the fowl, which are considered to be typical of behavior systems in other species. Aspects of neural development are examined and found to facilitate our understanding of a wide range of developmental phenomena, such as critical periods and irreversibility. Finally, various examples of classical conditioning and instrumental learning are analyzed in terms of the type of structures involved, and they are related to general developmental processes.

RESUMEN

In Experiment 1, 15 behavior patterns of male paradise fish (Macropodus opercularis; n = 72) toward a male conspecific, a male of another species, or no stimulus were recorded, both in home and novel situations. In Experiment 2, the same behaviors were recorded in a runway, and the same stimuli were used as reinforcers in the goal box (n = 18). A typical learning curve was seen when the subject found a male paradise fish in the goal box, learning was followed by apparent extinction when another species was found in the goal box, and few signs of learning were seen when the goal box was empty. Performance of the fish in both experiments can be accounted for by a strong aggressive motivation, a less strong but clear general curiosity, and habituation to the experimental procedure. In contrast to recent assertions in the literature, we conclude that aggressive behavior clearly can serve as a reinforcer in an instrumental learning situation.

Asunto(s)

RESUMEN

Burmese red junglefowl (Gallus gallus spadiceus) chicks were reinforced at 5 days old with a mealworm at the end of a runaway in the presence of a maternal food call. Two food calls were used, one made to a highly preferred food item (a mealworm) and one made to a less preferred food item (chick crumbs). Chicks initially approached the food call made to the mealworm faster regardless of reinforcement contingencies, but by the 3rd day of training chicks responded faster to the call that was reinforced. These results indicate that functional experience can modify preexisting response tendencies to food-calling stimuli. We discuss the implications of these results for the interpretation of published accounts that chickens use food calls deceptively.

Asunto(s)

RESUMEN

As part of a Controlled Ecological Life Support System (CELSS) for long term human travel and habitation in space, the resources in solid waste may be regenerated through the microbiological process of composting. This would release CO2 for photosynthetic uptake while transforming the waste to a smaller volume and weight of stabilized and sanitized compost. To continue the biodegradation and complete the cycling of nutrients, the compost would be incorporated into soil used in growing food crops. To minimize the weight and volume of the composting facility, the rate of the transformation should be maximized. This is realizable through ventilative removal of heat in reference to a biologically favorable temperature ceiling, and maintenance of a thoroughly oxygenated state. A preliminary design for a composting system for use in a spacecraft and/or permanent space station is proposed.

Asunto(s)

RESUMEN

A composting physical model with an experimental chamber with a working volume of 14 x 10 cm (0.5 ft) was designed to avoid exaggerated conductive heat loss resulting from, relative to field-scale piles, a disproportionately large outer surface-area-to-volume ratio. In the physical model, conductive flux (rate of heat flow through chamber surfaces) was made constant and slight through a combination of insulation and temperature control of the surrounding air. This control was based on the instantaneous conductive flux, as calculated from temperature differentials via a conductive heat flow model. An experiment was performed over a 10-day period in which control of the composting process was based on ventilative heat removal in reference to a microbially favorable temperature ceiling (temperature feedback). By using the conduction control system (surrounding air temperature controlled), 2.4% of the total heat evolved from the chamber was through conduction, whereas the remainder was through the ventilative mechanisms of the latent heat of vaporization and the sensible temperature increase of air. By comparison, with insulation alone (the conduction control system was not used) conduction accounted for 33.5% of the total heat evolved. This difference in conduction resulted in substantial behavioral differences with respect to the temperature of the composting matrix and the amount of water removed. By emphasizing the slight conduction system (2.4% of total heat flow) as being a better representative of field conditions, a comparison was made between composting system behavior in the laboratory physical model and field-scale piles described in earlier reports. Numerous behavioral patterns were qualitatively similar in the laboratory and field (e.g., temperature gradient, O(2) content, and water removal). It was concluded that field-scale composting system behavior can be simulated reasonably faithfully in the physical model.

Asunto(s)

RESUMEN

Four pigeons were trained to peck at a 37-spot stimulus for food. While this training continued, two of the pigeons received extinction training to a 21-spot stimulus and the other two received extinction training to a plain white stimulus. In a subsequent generalization test of stimuli which varied in number of spots, pigeons extinguished on the 21-spot stimulus responded most to the 52- and 69-spot stimuli. This "peak shift" in responding is functionally similar to "supernormality" seen in the egg-retrieval responses of gulls. Possible causes of these two phenomena are discussed and compared.

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)