Analysis of an algae-based CELSS. Part 1: model development.

A steady state chemical model and computer program have been developed for a life support system and applied to trade-off studies. The model is based on human demand for food and oxygen determined from crew metabolic needs. The model includes modules for water recycle, waste treatment, CO2 removal and treatment, and food production. The computer program calculates rates of use and material balance for food. O2, the recycle of human waste and trash, H2O, N2, and food production supply. A simple non-iterative solution for the model has been developed using the steady state rate equations for the chemical reactions. The model and program have been used in system sizing and subsystem trade-off studies of a partially closed life support system.

Gunshot wounds to the head: a perspective.

Craniocerebral gunshot wounds are a significant cause of injury and death in the United States. However, despite reports of occasional unexpectedly favorable outcome in surgically treated patients, these injuries have been viewed pessimistically and indeed have generally been excluded from modern studies of head injuries, which have concentrated on closed head injuries. A review of 143 victims of craniocerebral gunshot wounds admitted to Hermann Hospital, Houston, Texas, during a recent 30-month period confirmed that a few apparently neurologically devastated patients can be saved. A detailed analysis of these patients, including demographic details, general and neurological condition, anatomic injuries, laboratory findings, surgical care, neurological course, and neurological and functional outcome follows. The helpfulness of early resuscitation and appropriate criteria for surgery need to be studied using historic or randomized controls.

Clinicopathological correlations of disseminated intravascular coagulation in patients with head injury.

To try to define the significance of disseminated intravascular coagulation (DIC) in head-injured patients, we correlated clinical, laboratory, and pathological findings in 16 patients with head injury as their main problem who had DIC, who died within 4 days of injury, and who were examined postmortem. Patients were ranked according to the number of abnormal laboratory screening tests for DIC and the severity of these abnormalities. The most frequently abnormal laboratory tests were the fibrinogen degradation products and fibrinogen, followed in order by the activated partial thromboplastin time, prothrombin time, and thrombin time. The platelet count was the least abnormal value. The patients with the fewest abnormalities had the least abnormal computed tomographic scans. Autopsy reports revealed necrosis and bleeding in the brain and in a number of other organs, particularly the lungs. Microthrombi were not reported in the original autopsy reports. However, when these cases were reevaluated and their slides were stained with an immunoperoxidase technique using rabbit anti-human fibrinogen antiserum, microthrombi were seen frequently. Large microthrombi were more common in patients who had died within less than 24 hours, suggesting a relationship to death or to less time for lysis. In order of frequency, the brain/spinal cord, liver, lungs, kidneys, and pancreas were most commonly affected, and the liver, pituitary gland, pancreas, thymus, brain/spinal cord, large intestine, kidneys, and lungs had the greatest density of microthrombi. Pulmonary dysfunction had been a frequent problem in these patients, which may have been related to the high incidence of microthrombi and bleeding found in the lungs.(ABSTRACT TRUNCATED AT 250 WORDS)

Civilian gunshot wounds: the limits of salvageability.

Patients who have suffered gunshot wounds in civilian settings, who present with posturing and in whom the bullet has passed through the geographical centre of the brain have generally not been felt to be salvageable. However, surprisingly favourable outcomes in two such patients have led us to believe that some such patients may deserve aggressive treatment.

Neurological course and correlated computerized tomography findings after severe closed head injury.

This study includes 124 patients with closed head injuries and with Glasgow Coma Scale (GCS) scores of less than or equal to 8, who were admitted over a 7 1/2-month period. The time at which death occurred after injury was bimodal: deaths occurred either within 48 hours or after 7 days or longer after injury. Neurological deterioration, however, occurred with equal frequency on Days 2 to 7 after injury. Patients who survived the first 48 hours and then suffered neurological deterioration did not differ from the total population in age, sex, GCS scores on admission, or pupillary reactivity, but had a much higher incidence of intracranial hematomas of all types. Deterioration occurred three times more frequently in those with hematomas than in those with diffuse brain injury. Patients who deteriorated were rarely among the 35% of those who rapidly improved in the first 48 hours (4 points or more on the GCS). Computerized tomography (CT) scans of those deteriorating (24 patients) could be divided into four categories: 1) those without new mass effect (eight cases); 2) those with new or increased hemispheric edema (six cases); 3) those with generalized edema (two cases); and 4) those with focal or lobar areas of new edema or hemorrhage (eight cases). Of the patients in coma who deteriorated, 19% had large, delayed intracerebral hematomas. In 11 of 16 cases deteriorating with new mass effect, prior compression by overlying extracerebral hematoma, disruption of brain by intracerebral hematoma, or preexisting hemispheric edema preceded the brain swelling that caused deterioration. Areas of disruption or compression on CT scan typically developed decreased attenuation 2 to 7 days after injury, but did not cause deterioration unless new mass effect accompanied the lucency appearing on CT scan. A mortality rate of 29% was achieved for the 124 cases, which were managed with early evacuation of hematomas and control of intracranial pressure. Certain methods are suggested for evaluating therapy and for comparing clinical series.

Model for genetic control of Heliothis virescens.

A model was developed which corrects and extends an earlier one proposed for the control of the tobacco budworm, Heliothis virescens (F.), through hybrid male sterility. Population suppression is effected through the release into natural populations of the backcross progeny of a hybrid between H. virescens and a related species. Thereafter, the system perpetuates itself in nature through continual backcrossing of the fertile backcross females to native H. virescens males. When the proportion of backcross hybrid females in the total population is large enough to draw off the insemination potential of the native males, the native females fail to replace themselves. The present model demonstrated that the ratio of released backcross hybrids to natural H. virescens remains constant in a closed population. Furthermore it was shown that the release ratio necessary to achieve extinction of a closed population is related to the number of females that a male can inseminate and to the population growth rate. Release ratios required to slow natural population growth and to lessen the impact damage of releases on crop plants were also examined. Effects of selection against the backcross females on the predictions of the model were explored.

The detection of sympatric sibling species using genetic correlation analysis. I. Two loci, two gamodemes.

Four models are presented describing zygotic frequencies at two loci for one or two sympatric but genetically differentiated populations of "gamodemes." Linkage disequilibrium within gamodemes is allowed in two of the models. Maximum likelihood criteria are used to fit the models to the observed numbers of zygotes in a sample. A fitting-testing sequence for choosing a best model is described and the power of the test is analyzed. The statistical characteristics of the genetic parameter estimates were examined by simulation studies. In general, estimates were reliable when allele frequency differences between gamodemes were greater than 0.30 at both loci. This method may be used to study the population structure of samples with fewer heterozygotes than expected for Hardy-Weinberg populations, including the detection and genetic description of sibling species having overlapping ranges.--An example is given for Drosophila longicornis and D. propachuca, two sibling species within the mulleri complex of the repleta group which have been studied in detail using more conventional techniques. The reanalysis using the approach derived in this paper confirmed the reproductive isolation of these two species, and hinted at the possibility of further subdivision within D. propachuca.