Showing papers by "University of Missouri published in 1984"

Small-angle X-ray-scattering investigation of submicroscopic porosity with fractal properties

Abstract: A method is developed for analyzing the outer part of the small-angle x-ray or neutron scattering curve for porous scatterers in which the pore boundaries can be described by fractals. When the results are applied to the scattering data from a lignite coal, the fractal dimension of the boundary surface of the pores in this coal is found to be 2.56 \ifmmode\pm\else\textpm\fi{}0.03.

Relationships between crystal structure and magnetic properties in Nd 2 Fe 14 B

Abstract: Determination of the crystal structure of ${\mathrm{Nd}}_{2}$${\mathrm{Fe}}_{14}$B, a new ternary phase, is reported. It has recently been demonstrated that permanent magnets having large coercivities and energy products can be formed from this phase, underscoring its potential technological importance. We relate the crystal structure and intrinsic magnetic properties by considering analogies with previously known rare-earth---transition-metal materials.

Percutaneous balloon aortic valvuloplasty: Results in 23 patients

Abstract: Percutaneous balloon aortic valvuloplasty (BAV) was performed in 23 consecutive patients with valvular aortic stenosis with no associated cardiac defects. The patients were 2 to 17 years old and were referred from 12 hospitals in 4 states. The balloon was positioned across the aortic valve and inflated to pressures of 80, 100, then 120 psi. Each inflation lasted 5 to 10 seconds. The arterial and venous catheters were connected together outside the groin to avoid excessive increase in left ventricular pressure during total aortic valve occlusion with the inflated balloon. Peak systolic aortic valve pressure gradient and cardiac output were measured before and 15 minutes after BAV. There was no significant change in cardiac output, but all patients had a lessened gradient. The gradient before BAV was 113 +/- 48 mm Hg, decreasing to 32 +/- 15 mm Hg after BAV (p less than 0.01). The left ventricular peak systolic pressure decreased from 221 +/- 54 to 149 +/- 21 mm Hg (p less than 0.01). No aortic regurgitation was noted in 13 patients and very mild aortic regurgitation was noted in 10 patients after BAV. The balloons were 10 to 20 mm in diameter, chosen at least 1 mm smaller than the diameter of the aortic valve anulus. Pressures of 100 to 120 psi were required to achieve full inflation of the balloons. Six patients had repeat cardiac catheterization studies 3 to 9 months after BAV. In none was there a significant change in peak systolic aortic valve pressure gradient or cardiac output compared with the study immediately after valvuloplasty.

A Comparison of Exact Approaches for Solving the Multiple Constrained Resource, Project Scheduling Problem

Abstract: A recurring problem in managing project activity involves the allocation of scarce resources to the individual activities comprising the project Resource conflict resolution decisions must be made whenever the concurrent demand for resources by the competing activities of a project exceeds resource availability. When these resource conflict resolution decisions arise, project managers seek direction on which activities to schedule and which to delay in order that the resulting increase in project duration is the minimum that can be achieved with the given resource availabilities. The procedures examined in this paper are all designed to provide for this type of decision support. Each procedure examined is enumerative based, methodically searching the set of possible solutions in such a way that not all possibilities need be considered individually. The methods differ in the manner in which the tree representing partial schedules is generated and is saved, and differ in the methods which are used to identify and discard inferior partial schedules. Each procedure was found to be generally superior on a specific class of problems, and these classes are identified.

Predicting the Onset of Cigarette Smoking in Adolescents: A Longitudinal Study

Abstract: In a longitudinal study, the second-year-smoking status of adolescents who were initially Nonsmokers or Triers was predicted from their Year 1 standing on three types of social psychological variables: Ajzen and Fishbein's factors (predicting smoking transitions from attitudes, normative beliefs and behavioral intentions about smoking); Jessor and Jessor's distal variables (predicting smoking transitions from more generalized personality and perceived environment factors), and smoking environment variables (predicting smoking transitions from the extent of smoking models in an adolescent's social milieu). The predictive power of these three categories of factors was compared. All three classes of social psychological variables were statistically significant predictors of smoking transition, although the Ajzen and Fishbein variables were more important for Triers while the Jessor and Jessor and smoking environment variables were more important for initial Never Smokers. Moreover, each category of variables made independent contributions to the prediction of smoking transition. Finally, there were several age and sex differences in the relative importance of predictor variables. Implications of these findings for the design of effective smoking prevention programs are discussed. Smoking prevention programs might be more effective if they were aimed at a specific high risk audience (as identified by the current study) rather than at a general adolescent population.

The relationship between physical growth and a newborn reflex

Abstract: Young infants both grow at a very rapid rate and show dramatic changes in body composition. The behavioral consequences of somatic growth have been little explored. Here we report three studies on the relationship between body-build changes and a newborn reflex, stepping. Study 1 compared the number of steps and several body-build measures in 40 infants seen at 2, 4, and 6 weeks. At each age, overall arousal was the best predictor of steps. At 4 weeks, however, those infants who gained weight and became “chubby” most rapidly stepped less. Infants gained weight and added fat at the most rapid rate between 2 and 4 weeks. In Study 2, we manipulated leg mass by adding small weights to the legs. Infants stepped less and with weaker flexion movements when the legs were weighted. In Study 3, we reduced the effects of leg mass by submerging infants’ legs in water. Stepping rate increased and joint flexions were greater. We proposed that muscle strength development may not be synchronous with mass increase and that peripheral as well as central nervous system factors contribute to infant behavioral development. The disappearance of stepping is better explained by asynchronous physical growth than by previous hypotheses.

Outcome assessment in clinical trials. Evidence for the sensitivity of a health status measure.

Abstract: Health status measures are conceptually relevant to the assessment of clinical outcome in the rheumatic diseases, but their ability to detect meaningful changes in health has not been clearly demonstrated. This report describes the performance of a self-administered health status questionnaire in a randomized, double-blind, 21-week comparison of placebo, oral gold, and injectable gold in rheumatoid arthritis patients. Outcome was assessed by standard clinical measures, including joint count, grip strength, and laboratory tests, and by the Arthritis Impact Measurement Scales, a reliable and valid health status measure that assesses physical disability, psychological status, and pain. Data from the clinical and health status measures produced highly similar conclusions: injectable and oral gold are more effective than placebo for rheumatoid arthritis, and injections are slightly more effective than oral gold. The health status measure was thus quite sensitive to clinically meaningful drug-induced improvements. These findings provide justification for the further application of health status measures to clinical trials of chronic disease.

Motor evoked potentials from transcranial stimulation of the motor cortex in humans.

Abstract: Electrical testing of central nervous system pathways is assuming increasing importance in clinical medicine However, there is no direct monitor of the motor system We previously reported using a motor evoked potential created by direct excitation of the spinal cord, placing a stimulating electrode over the corticospinal tract area To produce a less invasive test, we now use direct transcranial stimulation of the motor cortex through the scalp or direct stimulation of the motor cortex itself during operation A descending signal can be recorded over the spinal cord and in the peripheral nerves where no retrograde sensory signals should be able to descend This motor cortex stimulation produces contralateral limb movements and selective activation of the peripheral nerves of a limb The characteristics of this signal are similar to those described in the neurophysiological literature for a descending motor signal With a depth electrode, it was found that the signal was strongest in the spinal cord near the corticospinal tracts and in the anterior horn cell area A set of lesioning studies showed that most of the signal travels in the area of the corticospinal tract, with some traveling in the ventral portion of the spinal cord, perhaps in the anterior corticospinal tract Section of the pyramid essentially abolishes the signal, but lesioning of the red nucleus does not This test offers an electrical assessment of the motor system that can be useful in experimental work on spinal cord and brain function It has potential clinical applicability in humans

Functional study of the Caenorhabditis elegans secretory‐excretory system using laser microsurgery

Abstract: Individual cells of the Caenorhabditis elegans secretory-excretory system were ablated by laser microbeam in various larval stages. Effects on growth, molting, osmoregulation, fertility, longevity, and dauer larva formation were tested. Single-cell ablations did not prevent subsequent molting, but ablation of the pore cell or the duct cell resulted in the absence of the normal cuticular lining of the excretory duct following a molt. When the pore cell, duct cell, or excretory cell was ablated, the animals filled with fluid within 12-24 hr and died within a few days, producing very few progeny. Ablation of the excretory gland cell, on the other hand, had no obvious developmental or behavioral effects. Excretory activity was monitored in dauer larvae by observing pulsation of the excretory duct in conditions of differing osmolarity. The rate of pulsation was quite variable over time in conditions of low osmotic strength, but average five- to six-fold higher than that observed in buffered saline. These observations, combined with the effects of laser ablation, lead to the conclusion that one function of the excretory system is osmoregulation.

Lexical agraphia. Further support for the two-system hypothesis of linguistic agraphia.

Abstract: Eight patients with acquired agraphia were studied using the same writing tests and were compared with normal and brain-damaged controls. Four patients fulfilled the criteria for lexical agraphia and on CT scan had lesions of the posterior angular gyrus that spared the supramarginal gyrus. The other 4 fulfilled the criteria for phonological agraphia. They had lesions on CT scan that were similar to those found in previously described patients with phonological agraphia. Their lesions involved the supramarginal gyrus or insula deep to it and spared the angular gyrus. These studies support the hypothesis that there are two dissociable spelling systems and that these spelling systems are disrupted by focal lesions in separate but distinct brain regions. Further studies investigated the relationships between phonological agraphia and phonological dyslexia (alexia), and lexical agraphia and surface dyslexia (lexical alexia). The data support the hypothesis that individual systems subserve the four processes of phonological spelling, phonological reading, lexical spelling and lexical reading.

Transluminal balloon coarctation angioplasty: Experience with 27 patients

Abstract: Transluminal balloon angioplasty (BA) was performed in 27 consecutive patients with coarctation of the aorta (COA), including 7 infants with preductal COA, 7 patients with restenosed COA after surgical repair, and 13 older children and 1 adult with unoperated COA. The patients were 4 days to 27 years old. The balloon was positioned across the COA and inflated sequentially to pressures of 100 and 120 psi, each inflation lasting for 5 to 10 seconds. Peak systolic pressure gradient (PSG) across the COA was recorded and an aortogram was performed before and immediately after BA. PSG also was recorded during follow-up studies performed in 13 patients 3 to 24 months after BA. BA was performed without complications in each patient. Immediately after BA, the mean PSG was reduced from 49 ± 21 to 10 ± 7 mm Hg (p

Division of attention: age differences on a visually presented memory task.

Abstract: Young and old adults were compared in their efficiency of remembering concurrently presented series of letters and digits in three separate experiments. Instructions and payoffs to vary attentional emphasis across the two types of material in different conditions allowed the examination of attention-operating characteristics in the two age groups. Strategy-independent measures derived from these attention-operating characteristics revealed that older adults exhibited greater performance deficits than young adults when dividing their attention between the two tasks, even though dual-task difficulty was individually adjusted for each subject. It was concluded that either the total amount of attention available for distribution or the efficiency of its allocation decreased with age even though the ability to vary one’s attention between concurrent tasks in response to instructions and payoffs remained intact.

Instantaneous Feedback Controlled PWM Inverter with Adaptive Hysteresis

Abstract: A new control strategy for a PWM inverter controlled through adaptive hysteresis in an instantaneous feedback loop is theoretically analyzed and verified through simulations and a low-power experimental circuit. This control gives excellent performance under various load conditions, and it is especially effective in reducing load injected harmonics.

The snapping hip syndrome

Abstract: The snapping hip syndrome is a symptom complex characterized by hip pain and an audible snapping of the hip with exercise typically seen in young individuals. "External" and "internal" etiologies have been described, although the "internal" etiology is poorly understood. A clinical, radiographic, and anatomical study of eight patients with this disorder, secondary to an internal etiology, was undertaken to aid in the diagnosis and surgical treatment. Iliopsoas bursography with cineradiography revealed subluxation of the iliopsoas tendon to be an apparent cause of the snapping hip. The anatomy of the hip in relationship to the iliopsoas tendon is defined with the anterior inferior iliac spine, iliopectineal eminence, and lesser trochanter assuming a significant role in the syndrome. An operative approach involving a partial release and lengthening of the iliopsoas tendon, with minimal resection of a lesser trochanteric bony ridge, if involved, is described.

Antibodies to a nuclear/nucleolar antigen in patients with polymyositis overlap syndromes

Abstract: A precipitating antigen-antibody system has been characterized that occurs in patients with polymyositis. At least half of the patients not only have polymyositis but also have scleroderma. The proposed name for this antigen found in calf thymus extract (CTE) is PM-Scl, to indicate the almost universal presence of polymyositis and the frequent occurrence of scleroderma in the patients who make antibodies to this antigen. The antigen is probably nucleolar since all sera which precipitate with the PM-Scl antigen stain the nucleoli of Hep2 cells by indirect immunofluorescence. The PM-Scl immune system is a distinctive one different from the other known precipitins that occur in patients with polymyositis and dermatomyositis including Jo1, nRNP, and Mi. This PM-Scl antigen and its antibody represent one system which constitutes part of the reactions previously designated as PM1. Interlaboratory exchange of sera and extracts have established the unique nature of this reaction which occurs in patients with inflammatory myopathy.

Mechanisms Underlying the False Consensus Effect The Special Role of Threats to the Self

Abstract: The current studies investigated the role of self-serving motivations in the False Consensus Effect (FCE). There were two major goals. First, the studies tested whether consensus estimates would be increased when judges receive threats to self in the form of failure feedback about their performance on an experimental task. The second goal of the studies was to investigate whether self-knowledge plays a special role in the FCE beyond the use of the self as simply a single available case in memory. The current findings indicated that judges indeed use the behavior of an available case (whether the self or an other) in making inferences about a target group. Moreover, under success conditions, the available case information was sufficient to account for the extent of perceived consensus. However, under failure feedback, a judge's own behavior increased estimates above and beyond the effect of information about an available individual When the self is threatened, perceptions of consensus may be increased by a...

Ammonium uptake in Lemna gibba G 1, related membrane potential changes, and inhibition of anion uptake

Abstract: In N-starved (−N) fronds of Lemna gibba L. G 1, NH4+ uptake rates were several-fold those of NO3−-supplied (+N) fronds. NO3−, uptake in +N-plants was slow and not inhibited by addition of NH4+. However, in −N-plants with higher NO3− and still higher NH4+ uptake rates, addition of NH4+ immediately reduced the NO3− uptake rates to about one third until the NH4+ was consumed. The membrane potential (Em) decreased immediately upon addition of NH4+ in all fronds, but whereas depolarisation was moderate and transient in +N-plants, it was strong, up to 150 mV, in N-starved plants, where Em remained at the level of the K+ diffusion potential (ED) until NH4+ was removed. In N-starved plants NH4+ uptake and membrane depolarisation showed the same concentration dependence, except for an apparent linear component for uptake. Phosphate uptake was inhibited by NH4+ similarly to NO3− uptake, but only in P- and N-starved plants, not after mere P starvation. Influx of NO3− and H2PO 4− into the negatively charged cells of Lemna is mediated by anion/H+ cotransport, but NH4+ influx can follow the electrochemical gradient. Its saturating component may reflect a carrier-mediated NH4+ uniport, the linear component diffusion of NH4+ or NH3. Inhibition of anion/H+ cotransport by high NH4+ influx rates may be due to loss of the proton-driving force, ΔμH+, across the plasmalemma. Reversible inhibition by NH4+ of the H+ extrusion pump may contribute to the finding that ΔμH+ cannot be reconstituted in the presence of higher NH4+ concentrations.

Resource use by stream-dwelling rock bass and smallmouth bass

Abstract: We examined food and habitat use of sympatric smallmouth bass Micropterus dolomieui and rock bass Ambloplites rupestris in the Current and Jacks Fork rivers, Missouri. Use of food resources was similar between species and within a species. On a total caloric basis, the importance of prey ranked crayfish > fish > insects. The similarities of both prey types and the size selection of prey indicated that food resources were not a mechanism of ecological segregation between rock and smallmouth bass. Habitat use was evaluated by underwater observation. Location of both species was highly correlated with some aspect of cover, especially woody structure. Although cover use overlapped among size classes and species, rock bass were more often associated with rootwads and smallmouth bass with log complexes (aggregates of logs and branches). Cover use was independent of rock bass size, but smallmouth bass shorter than 350 mm long more often used vegetation and boulders and were more often found in open wate...

An Integer Programming Algorithm with Network Cuts for Solving the Assembly Line Balancing Problem

Abstract: In this paper, we describe an integer programming algorithm for assigning tasks on an assembly line to work stations in such a way that the number of work stations is minimal for the rate of production desired. The procedure insures that no task is assigned to a work station before all tasks which technologically must be performed before it have been assigned precedence restrictions are not violated, and that the total time required at each work station performing the tasks assigned to it does not exceed the time available cycle time restrictions are not violated. The procedure is based on a systematic evaluation enumeration of all possible task assignments to work stations. Significant portions of the enumeration process are performed implicitly, however, by utilizing tests described in the paper which are based on the specific structure of the line balancing problem. An artifice termed a network cut is also developed which eliminates from explicit consideration the assignment of tasks to work stations where such assignments would not lead to improved line balances. Results reported demonstrate that the procedure can obtain optimal balances for assembly lines with between 50 and 100 tasks in a reasonable amount of computation time and with modest computer storage requirements.

Phosphate uptake inLemna gibba G1: energetics and kinetics.

Abstract: Phosphate uptake was studied by determining [32P]phosphate influx and by measurements of the electrical membrane potential in duckweed (Lemna gibba L.). Phosphate-induced membrane depolarization (ΔE m ) was controlled by the intracellular phosphate content, thus maximal ΔE m by 1 mM H2PO 4 - was up to 133 mV after 15d of phosphate starvation. The ΔE m was strongly dependent on the extracellular pH, with a sharp optimum at pH 5.7. It is suggested that phosphate uptake is energized by the electrochemical proton gradient, proceeding by a 2H+/H2PO 4 - contransport mechanism. This is supported also by the fusicoccin stimulation of phosphate influx. Kinetics of phosphate influx and of ΔE m , which represent mere plasmalemma transport, are best described by two Michaelis-Menten terms without any linear components.

Sjögren's syndrome in MRL/l and MRL/n mice.

Abstract: Six autoimmune murine models (MRL/l, MRL/n, NZB, NZB/NZW, PN, C57BL/6J-lpr/lpr) were compared with normal control C57BL/6J and DBA/2 mice to determine if spontaneous autoimmune disease was associated with evidence of Sjogren's syndrome. Schirmer tests documented dry eyes in NZB/NZW and PN mice; other autoimmune strains and controls had normal tear formation. All autoimmune mice had conjunctivitis, but this abnormality was most severe in the PN strain. Ninety-eight percent of MRL/1 and MRL/n mice had mononuclear cell infiltrates in lacrimal glands, and salivary glands were involved to a lesser degree. New Zealand mice and PN mice had smaller gland lesions. The extensive gland destruction in MRL/l and MRL/n mice suggested that these substrains merit further studies as animal models of Sjogren's syndrome.

Contrasting fluid/rock interaction between the Notch Peak granitic intrusion and argillites and limestones in western Utah: evidence from stable isotopes and phase assemblages

Abstract: The Jurassic Notch Peak granitic stock, western Utah, discordantly intrudes Cambrian interbedded pure limestones and calcareous argillites. Contact metamorphosed argillite and limestone samples, collected along traverses away from the intrusion, were analyzed for δ18O, δ13C, and δD. The δ13C and δ18O values for the limestones remain constant at about 0.5 (PDB) and 20 (SMOW), respectively, with increasing metamorphic grade. The whole rock δ18O values of the argillites systematically decrease from 19 to as low as 8.1, and the δ13C values of the carbonate fraction from 0.5 to −11.8. The change in δ13C values can be explained by Rayleigh decarbonation during calcsilicate reactions, where calculated \(\Delta ^{13} {\text{C}}_{\left( {{\text{CO}}_{\text{2}} - {\text{cc}}} \right)}\) is about 4.5 permil for the high-grade samples and less for medium and low-grade samples suggesting a range in temperatures at which most decarbonation occurred. However, the amount of CO2 released was not anough to decrease the whole rock δ18O to the values observed in the argillites. The low δ18O values close to the intrusion suggest interaction with magmatic water that had a δ18O value of 8.5. The extreme lowering of δ13C by fractional devolatilization and the lowering of δ18O in argillites close to the intrusion indicates oxgen-equivalent fluid/rock ratios in excess of 1.0 and X(CO2)F of the fluid less than 0.2. Mineral assemblages in conjunction with the isotopic data indicate a strong influence of water infiltration on the reaction relations in the argillites and separate fluid and thermal fronts moving thru the argillites. The different stable isotope relations in limestones and argillites attest to the importance of decarbonation in the enhancement of permeability. The flow of fluids was confined to the argillite beds (argillite aquifers) whereas the limestones prevented vertical fluid flow and convective cooling of the stock.

Integrated detonator delay circuits and firing console

Abstract: A detonation system for use with supply of electrical energy has user operable firing console for selectably transmitting unit identification information, firing delay time information and selections from a command set including Output, Delay, Fire (Time), Abort, Power Up (Arm), Input, and Store. The console displays responses or information digested from responses by electrical delay detonators to the commands. The detonators have explosive, a capacitor for storing energy from the supply to set off the explosive, circuitry for charging the capacitor from the supply and transferring the energy from the capacitor to the explosive in response to first and second signals generated in response to the commands. Each detonator can be programmed with a unique identification number and delay time. The time base in each detonator can be compensated so that errors in the time base are obviated so as to achieve the correct delay. Security code circuitry and software are described so that each detonator can only be set off by authorized users.