Design concepts for bioreactors in space

Microbial food sources are becoming viable and more efficient alternatives to conventional food sources, especially in the context of closed ecological life support systems (CELSS) in space habitats. Two bioreactor design concepts presented represent two dissimilar approaches to grappling with the absence of gravity in space habitats and deserve to be tested for adoption as important components of the life support function aboard spacecraft, space stations and other extra-terrestrial habitats

Crocodiles as dinosaurs: Behavioural thermoregulation in very large ectotherms leads to high and stable body temperatures

Empirical field data describing daily and seasonal cycles in body temperature (Tb) of free-ranging Crocodylus porosus (32-1010 kg) can be predicted by a mathematical analysis. The analysis provides a mechanistic explanation for the decreased amplitude of daily cycles in Tb and the increase in 'average' Tb with increasing mass. Assessments of 'average' daily Tb were made by dividing the integral of the difference between measured values of Tb and minimum operative temperature by the period of integration, to yield a thermal index expressing relative 'warmth' of crocodiles. The average daily Tb of a 1010 kg crocodile was 3.7 degrees C warmer than that of a 42 kg individual in summer and 1.9 degreesC warmer than that of a 32 kg individual in winter. The success of this mathematical approach confirms that crocodiles are simple ectotherms and that there is unlikely to be a significant contribution to their thermal biology from physiological mechanisms. Behaviour, however, is very important even in large individuals. Crocodiles in the field typically move daily between land and water in cycles that vary seasonally. We predicted Tb for the reverse of these behavioural cycles, which more than doubled seasonal fluctuations in Tb compared with the observed fluctuations. We were also able to predict the Tb of very large, dinosaur-sized crocodiles in a similar climate to that at our study site. A 10 000 kg 'crocodile', for example, would be expected to have a Tb of 31 degreesC in winter, varying by less than 0.1 degrees C during a day when operative temperatures varied by nearly 20 degrees C, from 20 to 38 degrees C. The study confirms that, in low latitudes at least, large dinosaurs must have had an essentially high and stable value of Tb, without any need for endothermy. Also, access to shade or water must have been crucial for the survival of large dinosaurs at low latitudes. Furthermore, the finding of increasing 'average' Tb as ectotherms grow larger may have implications for the metabolic rates of very large reptiles, because the Q10 effect could counteract the downscaling of metabolic rate with mass, an effect that seems not to have been recognised previously

Application of an Ultralight Aircraft to Aerial Surveys of Kangaroos on Grazing Properties

A Drifter ultralight aircraft was used as a platform for line-transect aerial surveys of three species of kangaroo in the sheep rangelands south-east of Blackall and north of Longreach in central-western Queensland in winter 1993 and 1994. Favourable comparisons between the results of ultralight surveys and those made from a helicopter flying the same transects and foot surveys along another set of transects, all within a few days of the ultralight survey, confirmed the expectation we had that an ultralight would be a satisfactory and much cheaper vehicle for conducting aerial surveys of kangaroos. The comparisons are even more favourable when data for the three species surveyed are combined, pointing to a problem in species identification and underlining the importance of using only experienced observers for aerial survey of kangaroos, whatever the platform. The use of an ultralight aircraft could have particular value where a comparatively small area, such as an individual sheep or cattle property, is under consideration. In this paper, we present the numerical comparisons, along with an evaluation of the practicability of using this type of aircraft. We also describe a possible future scenario in which an accreditation process could see approved kangaroo surveyors undertaking property assessments by ultralight, under contract to graziers or other interested parties

Allosteric Control Of Oxygen Binding By Haemoglobin During Embryonic Development In The Crocodile Crocodylus porosus: The Role Of Red Cell Organic Phosphates And Carbon Dioxide

The P50 of whole blood [30 degrees C, PCO2=2.08 kPa (15.6 mmHg)] decreases during embryonic development from approximately 6.7 kPa (50 mmHg) at 15 days to about half this value at hatching (86 days), paralleling a decrease in ATP from 100 to 5-10 micromole g-1 Hb. There is also a progressive changeover from embryonic to adult haemoglobin (HbA). A pulse of 2,3- diphosphoglycerate (2,3-DPG) (18 micromole g-1 Hb) occurs late in embryonic life. It has no effect on whole-blood oxygen-affinity and falls rapidly at hatching to values typical of post-hatchling crocodilians in general

Molecular Identification of Eimeria Species in Broiler Chickens in Trinidad, West Indies

Coccidiosis is an intestinal disease of chickens of major economic importance to broiler industries worldwide. Species of coccidia found in chickens include Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix, Eimeria praecox, and Eimeria tenella. In recent years, polymerase chain reaction (PCR) has been developed to provide accurate and rapid identification of the seven known Eimeria species of chickens. The aim of this study was to use species-specific real-time PCR (qPCR) to identify which of the seven Eimeria species are present in Trinidad poultry. Seventeen pooled fecal samples were collected from 6 broiler farms (2–5 pens per farm) across Trinidad. Feces were also collected from birds showing clinical signs of coccidiosis in two live bird markets (pluck shops). qPCR revealed the presence of five species of Eimeria (E. acervulina, E. maxima, E. mitis, E. necatrix, and E. tenella), but not E. brunetti or E. praecox. Mixed infections were detected on all broiler farms, and DNA of two highly pathogenic Eimeria species (E. tenella and E. necatrix) was detected in feces taken from clinically sick birds sampled from the two pluck shops

After the Miracle: A History and Analysis of the Massachusetts Fiscal Crisis: Being a Drama in Five Acts, with an Implied Invitation to the Reader to Participate in the Crafting of the Final Act

After the Miracle documents the factors that have shaped the recent political debate in Massachusetts and are likely to determine continuing economic and fiscal conditions in Massachusetts in the near future. The paper indicates that 1990 may begin a decade of real limits for Massachusetts. The economy has stagnated and the next two years will be a period of deep economic uncertainty. It is also clear that a resurgence, like that of the boom period of the eighties, is unlikely to be replicated. The 1980\u27s was a period when state-local spending in Massachusetts, propelled by the infusion of double-digit tax revenue yields, increased by about 72% (from $10.8 billion to$18.6 billion), an average rise of 9% each year. State spending excluding direct local aid distributions between the 1981 and 1989 fiscal years increased from $4.8 billion to$9.6 billion, or by over 12% on average per year. As a result, the state share of state-local spending increased from 45% to 52% of the total. By contrast, spending by cities and towns climbed by only 50% (from $6 billion to$9 billion) during this same period, or by 6% on average per year. The study shows that currently eight major cost centers dominate the state\u27s spending priorities. They are like giant termites, eating away at a revenue stream with limited growth potential. If their total allocation over the current fiscal year had not been essentially level-funded (on the basis of proposed major policy and program changes), they would have added more than one billion dollars to the Governor\u27s recommended budget for the 1991 fiscal year. Even as submitted, the $8,039 billion in budgetary requests for seven major cost centers, excluding pensions, is$2.0 billion over actual expenditures for these same purposes just four years ago, a jump of over 34%. The major cost centers account for 68% of the Governor\u27s entire budget submission for next year as compared with 62% of total spending in the 1989 fiscal year. Estimated spending for all purposes other than the major cost centers, on the other hand, will be about 13% below actual expenditures for these same purposes two years ago

The Medical Informatics Group: Ongoing Research

Two current research projects within the Medical Informatics Group are described. The first, the Diabetes Data Management Project, has as its major goal the effective analysis, display, and summarization of information relevant to the care of insulin-dependent diabetics. These goals are achieved through the use of quantitative and qualitative modeling techniques, object-oriented graphical display methods, and natural language generation programs. The second research activity, the Hypertext Medical Handbook Project, emphasizes many aspects of electronic publishing and biomedical communication. In particular, the project explores machine-assisted information retrieval by combining user feedback with Bayesian inference networks

Supersymmetry in models with strong on-site Coulomb repulsion - application to t-J model

A supersymmetric way of imposing the constraint of no double occupancy in models with strong on-site Coulomb repulsion is presented in this paper. In this formulation the physical operators in the constrainted Hilbert space are invariant under local unitary transformations mixing boson and fermion representations. As an illustration the formulation is applied to the $t-J$ model. The model is studied in the mean-field level in the J=0 limit where we show how both the slave-boson and slave-fermion formulations are included naturally in the present approach and how further results beyond both approaches are obtained.Comment: 12 pages, Latex file, 1 figur

The Two-Dimensional S=1 Quantum Heisenberg Antiferromagnet at Finite Temperatures

The temperature dependence of the correlation length, susceptibilities and the magnetic structure factor of the two-dimensional spin-1 square lattice quantum Heisenberg antiferromagnet are computed by the quantum Monte Carlo loop algorithm (QMC). In the experimentally relevant temperature regime the theoretically predicted asymptotic low temperature behavior is found to be not valid. The QMC results however, agree reasonably well with the experimental measurements of La2NiO4 even without considering anisotropies in the exchange interactions.Comment: 4 Pages, 1 table, 4 figure

Application of Radio Telemetry to Studies of the Physiological Ecology of Vertebrates

We present some generalizations about the use of radio telemetry in physiological ecology, particularly to monitor body temperature and heart rate, drawn from work on free-ranging camels, echidnas, platypus, Tasmanian devils, quolls, crocodiles, bearded dragon lizards, goannas, freshwater turtles, and Queensland lungfish. We identify some potential pitfalls and describe some case studies, including the questions that drove the research and a brief review of some of the results