Showing papers by "University of Louisville published in 1968"
TL;DR: It was found that a man can work 12 hours per day on a 4-hours work/4-hours rest schedule for periods of at least 30 days but at a significant cost to his reserves for meeting emergencies such as sleep loss.
Abstract: Thirteen investigations were carried out as a part of an 8-year program of research on the performance effects of various work/rest schedules during confinement to a simulated aeorspace vehicle crew compartment. A total of 139 subjects were tested using a standard battery of performance tasks. The synthetic work approach used provided a reliable, face-valid, and sensitive technique for assessing complex operator performance.It was found that a man can work 12 hours per day on a 4-hours work/4-hours rest schedule for periods of at least 30 days. For shorter periods, a man can work 16 hours per day on a 4/2 schedule but at a significant cost to his reserves for meeting emergencies such as sleep loss. Circadian periodicities are found in psycho-physiological functions paralleled by similar periodicities in performance functions, the latter being subject to modification by special motivational instructions.
84 citations
TL;DR: Differences in ecology of these species were most clearly seen in their habitat preferences and distributions in the stream, their feeding habits, responses to temperature, and infestations by an harpacticoid copepod Attheyella carolinensis CHAPPUIS, and in other life history phenomena, particularly with regard to reproduction and growth.
Abstract: The ecology and life histories of Orconectes rusticus rusticus (GIRARD) and Cambarus tenebrosus HAY were investigated in a spring stream, Doe Run, Meade County, Kentucky, from September 1962 through September 1964. Differences in ecology of these species were most clearly seen in their habitat preferences and distributions in the stream, their feeding habits, responses to temperature, and infestations by an harpacticoid copepod Attheyella carolinensis CHAPPUIS, and in other life history phenomena, particularly with regard to reproduction and growth.
Cambarus tenebrosus was most abundant in the constant temperature areas of the headwaters of Doe Run. Orconectes r. rusticus was found only in the lower three-fourths of the stream. Water temperatures in the headwater area may have been too low (12 — 14 C) for optimal growth of the crayfish had it existed there. Adults of C. tenebrosus were primarily hypogean, but young and subadults frequented the open stream environment. Orconectes r. rusticus was primarily an open stream inhabitant, and was sympatric with C. tenebrosus subadults and young in the downstream areas. When C. tenebrosus occurred in the open environment, it was most abundant in association with vegetation, and hence, was more heavily infested with A. carolinensis than O. r. rusticus.
Detritus, mainly from fallen leaves and marl grazings, apparently formed the most important component of the diet of O. r. rusticus. Vascular plants, mainly fallen leaves from the riparian vegetation, constituted the main portion of the diet of C. tenebrosus; filamentous algae were widely used where and when they were present.
Orconectes r. rusticus eggs hatch in May. These hatchlings become mature in 15 months and females oviposit after 22 – 24 months from March —May. Sexual maturity is attained at a carapace length of about 18 mm; maximum size is 45 mm. Most animals die after about 2.5 years; however, some live for three years. Molting activity ceases in winter.
Cambarus tenebrosus young hatch in July and August. Most hatchlings remain in the burrows until October and November at which time they emerge in response to dominance behavior. Growth occurs throughout the winter months, and sexual maturity is attained in 20 – 22 months when the crayfish are about 40 mm in carapace length. Mature females oviposit during June and July after about 22–23 months, and probably again after 34–35 months. Mating occurs during the winter and spring. In Doe Run, maximum size attained is 65 mm carapace length. Cambarus tenebrosus probably lives for 36 – 38 months.
75 citations
TL;DR: The benthic macrofauna of a woodland spring-bank, Morgan's Creek, Kentucky, was studied between February 1963 and September 1964 at eight collecting sites as discussed by the authors, where the basic habitat type of the stream is a rubble-riffle complex Four stations (III, IV, VI, and VII) were located in riffle sections at different points along the stream and additional stations were established at the spring source (I), a cascade area (II), a pool (V), and a reach at the mouth of stream (VIII)
Abstract: The benthic macrofauna of a woodland springbrook, Morgan's Creek, Kentucky, was studied between February 1963 and September 1964 at eight collecting sites The basic habitat type of the stream is a rubble-riffle complex Four stations (III, IV, VI, and VII) were located in riffle sections at different points along the stream and additional stations were established at the spring source (I), a cascade area (II), a pool (V), and a reach at the mouth of the stream (VIII)
71 citations
TL;DR: Hydrogen bonding appeared to play a major role in neutral polysaccharide-concanavalin A precipitate formation, whereas both hydrogen bonding and electrostatic forces were implicated in polyelectrolyte-con cancanavalIn A complex-formation.
Abstract: 1. Concanavalin A formed precipitates with polyelectrolytes such as fucoidan, RNA, heparin and bacterial lipopolysaccharides. 2. Precipitate formation also occurred between ficoll and concanavalin A. 3. Precipitate formation between concanavalin A and dextran or soluble starch was induced by the incorporation of phosphate groups into the unreactive glucans. 4. Introduction of polar groups, such as acetate, formate and phosphate, into glycogen resulted in enhanced precipitation with concanavalin A, whereas the opposite effect was noted on incorporation of hydrophobic (methyl) centres. 5. Neutral sugars and salt partially inhibited complex-formation between polyelectrolytes and concanavalin A. 6. Concanavalin A–glycogen complexes could be dissociated with 5% (w/v) trichloroacetic acid or 44% phenol–water. 7. Concanavalin A lost its glycogen-complexing ability after phenol treatment. 8. Evidence is presented for the existence of common binding sites on concanavalin A for both neutral polysaccharides and polyelectrolytes. 9. Hydrogen bonding appeared to play a major role in neutral polysaccharide–concanavalin A precipitate formation, whereas both hydrogen bonding and electrostatic forces were implicated in polyelectrolyte–concanavalin A complex-formation.
68 citations
TL;DR: In this paper, observers were required to detect double jumps of a diffuse light spot jumping in a circular pattern and more intense noise pulses in a pulse train, at different combinations of stimulus and signal frequencies, higher signal frequency/stimulus frequency ratios, and lower stimulus frequencies.
Abstract: Observers were required to detect double jumps of a diffuse light spot jumping in a circular pattern and more intense noise pulses in a pulse train. Seven groups performed at different combinations of stimulus and signal frequencies, higher signal frequency/stimulus frequency ratios, and lower stimulus frequencies. Stimulus frequency was a more potent determiner of performance than signal frequency, and performance was not invariant within a given signal frequency/stimulus frequency ratio. Correlations of dependent measures were also examined.-Results are discussed with reference to various theories of vigilance behavior.
62 citations
TL;DR: Comparative determination of high affinity binding activity for cortisol and corticosterone in the sera of various species by equilibrium dialysis indicated considerable differences, which were independent of the ratio of cortisol to cortic testosterone present in the blood plasma.
61 citations
TL;DR: Thermodynamic data indicate that the interaction of AAG with the Δ4-3-ketosteroids is associated with a negative free energy change, composed of a negative enthalpy change and a positive entropy change.
51 citations
TL;DR: Genetic analysis of the kindred in this presentation indicates that the polyposis gene was transmitted as a simple mendelian dominant trait, and showed no significant deviation from the hypothesis that the sexes are equally affected inpolyposis.
Abstract: Genetic analysis of the kindred in this presentation indicates that the polyposis gene was transmitted as a simple mendelian dominant trait. The data showed no significant deviation from the hypothesis that the sexes are equally affected in polyposis; however, affected fathers produced a slight excess of affected sons, while affected mothers produced a marked excess of affected daughters which approached the P 0.05 level of significance. The incidence at birth of individuals with the polyposis gene was one in 6,850 for this Kentucky survey. Individuals possessing the polyposis gene had a relative biologic fitness of 84.85 per cent when compared with the general population. The penetrance of the polyposis gene in the kindred at the time of the investigation was 49.43 per cent. The mutation rate for the polyposis locus was 12 mutations per million loci per generation. Possible sources of error and bias entering into the above calculations have been discussed.
48 citations
TL;DR: The binding affinity of these steroids to α1-acid glycoprotein was found to follow the polarity rule in that the steroid with the least number of polar groups was bound most firmly.
42 citations
TL;DR: The interfibrillar spaces of skeletal muscle fibers in adult vertebrates contain two distinct membranous systems, the T system and the sarcoplasmic reticulum, and the suggestion that development of transversely oriented triads might occur in rodents after birth is suggested.
Abstract: The interfibrillar spaces of skeletal muscle fibers in adult vertebrates contain two distinct membranous systems, the T system and the sarcoplasmic reticulum. Most of the T system is oriented transversely between the fibrils. Occasionally, longitudinal connections between the transversely oriented T system are seen (14). The sarcoplasmic reticulum is, in general, oriented longitudinally between the fibrils. However, the terminal segments of the sarcoplasmic reticulum face the T system and show transverse orientation at this level. Two terminal segments of sarcoplasmic reticulum and a tubular element of the T system between these segments have been called a triad (13). A triad is found near each junction of the A and I bands in reptiles, birds, and mammals. Numerous investigators have noted that the space between the T system and the apposed sarcoplasmic reticulum is about 100 A and is remarkably constant. Revel (14) described rather regularly spaced, dense bridges traversing this space in bat muscle fibers. Similar dense bridges were reported (19) for rat muscle fibers, and evidence that these bridges are connections between the T system and sarcoplasmic reticulum has been presented (20). In a recent electron microscope study (1) on morphogenesis of rat skeletal muscle, sarcoplasmic reticulum was observed between the developing fibrils in 16.5-20-day rat fetuses; but triads were not reported in that study. In light microscope studies on skeletal muscle fibers from newborn mice and fetal guinea pigs, Veratti (17) observed an irregular reticulum in longitudinal sections. He found a regular reticulum, transversely oriented, in similar longitudinal sections of fibers from adult mice (17). The contrast in appearance of reticulum in light microscope studies when reticulum profiles in fibers from newborn and adult mice are compared led to the suggestion that development of transversely oriented triads might occur in rodents after birth. Electron microscope studies on skeletal muscle fibers from 19day rat fetuses have shown a striking sparsity of transversely oriented triads and a more numerous distribution of longitudinally oriented triads.
35 citations
TL;DR: The purpose of this communication is to re-examine the problem in the light of some new observations with hamster intestine and ascertain whether the lack of agreement between various laboratories may simply be a result of a failure to take into consideration the existence of significant differences between species.
Abstract: TRANSPORT of sugars and amino-acids in the small intestine occurs by apparently similar Na+-activated mechanisms which are believed to involve reversible binding of substrate to specific membrane receptors or carriers (for review, see ref 1) At some level of the transport process, interactions between sugars and amino-acids are known to occur as indicated by reciprocal inhibitory effects2–10 Various hypotheses have been advanced to explain these findings, but the observations from several different laboratories—taken collectively—seem contradictory to the point of making each of these hypotheses untenable The purpose of this communication is to re-examine the problem in the light of some new observations with hamster intestine and, using this information, to ascertain whether the lack of agreement between various laboratories may simply be a result of a failure to take into consideration the existence of significant differences between species
TL;DR: A review of the literature shows that several investigations have called attention to the close association of interfibrillar tubules and the Z line, which was identified as SR in further electron microscope studies on ske]etal muscle fibers of fetal and newborn rats.
Abstract: In adult skeletal muscle fibers of reptiles, birds, and mammals each sarcomere contains two transversely oriented triads. The triads are located near the two A-I junctions in the sarcomere. The central element of the triad is a tubule formed by invagination of the sarcolemma and the transverse tubules thus formed are called the T system (rE). The two lateral elements of the triad are terminal segments of the sarcoplasmic reticulum (SR). The terminal segments of SR are continuous with two networks of tubules, one traversing the M line level, the other the Z line level. Although a majority cf the tubules in these networks are longitudinally oriented, many of the tubules make transverse connections in the networks (6). The interfibrillar SR and T of adult mammlain muscle fibers have been described in many electron microscope studies as a continuum of sleeves with each fibril surrounded by one of the sleeves. In a recent report (1 l) concerned primarily with triads in muscle fibers of the 19 day fetal rat, an interfibrillar network of tubules was also described. This network of tubules, which extends uninterrupted in successive sarcomeres, is continuous with lateral elements cf triads. On the basis of this continuity the network was identified as SR (11). In further electron microscope studies on ske]etal muscle fibers of fetal and newborn rats, close contact between the network of tubules and the Z line has been observed. A review of the literature shows that several investigations have called attention to the close association of interfibrillar tubules and the Z line. In early electron microscope studies on breast muscle fibers of the adult fowl, Bennett and Porter (2) observed strands of SR extending from Z line to Z line across the interfibrillar space. Bennett and Porter (2) described the SR as sleeves around each fibril and viewed the strands of interfibrillar SR at the Z line level as structures attached to SR encircIing the Z line. In a recent study on developing muscle cells in embryonic and posthatched chicks, Allen and Pepe (1) found distinct Z lines in the 5 day embryo. The Z lines were occasionally associated with the interfibrillar tubular system, Tubules surrounding myofilaments at approximately 1.5 /1 intervals were found in the 4 day embryo. Although no distinct Z lines were seen in the 4 day embryo, material resembling the Z line was found in place of the tubule in several cases. In fibers from breast muscle of the posthatched chick, small tubular connections were seen between interfibrillar vesicles and the tubules surrounding the fibrils at the Z line level (I). In a report on cultured breast muscle fibers from the chick embryo, Shimada, Fischman, and Moscona (9) showed elegant electron micrographs of the interfibrillar network of SR tubules at the Z line level of the sarcomere. However, the relationship of the Z line to the network of tubules was not considered in that report (9). At the same time, another report (5) on cultured breast muscle fibers from the chick embryo showed the interfibrillar network of tubules and called attention to the fact
TL;DR: Another method has been developed for obtaining a soluble apoprotein from the low density lipoprotein (LDL) of human plasma in the density class 1.019 < d < 1.063, and both on gel filtration and analytical ultracentrifugation the soluble Apoprotein showed one peak, but on cellulose acetate electrophoresis it showed two bands, which suggests two differently charged components.
TL;DR: P passage of glucose and similar materials through an unstirred chloroform layer separating two aqueous compartments was greatly accelerated by addition to the chloroforms of any of a variety of phospholipid fractions extracted from human erythrocyte membranes, the lecithin-rich fractions being particularly disproportionately effective in enhancing the aQueous-to-aqueous transfer.
TL;DR: The results show that antigenicity and progesterone-binding affinity are independent properties of the α1-acid glycoprotein molecule.
TL;DR: Gas adsorption on solids, discussed statistical mechanical theory assuming localized adlayer and non-localized mobile layer adorption for first ad layer and nonlocalized adlayer on top as discussed by the authors.
TL;DR: The necessity for the exclusion of water in the preparation of previously reported sugar-phospholipid complexes in highly nonpolar vehicles was found not to apply when chloroform was used as the organic solvent.
TL;DR: The measurement of urea in arginase reaction mixtures using this reaction is described and a method was introduced which takes advantage of the different absorptivities of arginine, ornithine, and urea at 206 mμ.
TL;DR: A new method of calculating molecular crystal structures is proposed and tested that is markedly superior to those of the steepest-descent method, and calculation times are greatly decreased.
Abstract: A new method of calculating molecular crystal structures is proposed and tested. The repulsive portion of the nonbonded potential energy is fitted by a quadratic equation to yield a sum-of-squares description of the repulsive lattice energy. Minimization of this sum by full-matrix least squares yields good fits to the observed crystal structures of several hydrocarbons. The convergence properties of the method are markedly superior to those of the steepest-descent method, and calculation times are greatly decreased.
TL;DR: Electron microscopic observations of the lesions seen in the enzymatic induction of atherosclerosis in rabbits, the repair of surgically injured arteries in dogs, and the human atherosclerotic lesions in coronary arteries have lead to an hypothesis of atherogenesis.
TL;DR: A comparison of meristic and morphological characteristics in series of freshwater drum from the lower Ohio River, Kentucky, and Lake Winnebago, Wisconsin, indicates that statistically significant differences in some measurements along the long axis of the body as discussed by the authors.
Abstract: A comparison of meristic and morphological characteristics in series of freshwater drum from the lower Ohio River, Kentucky, and Lake Winnebago, Wisconsin, indicates that there are statistically significant differences in some measurements along the long axis of the body. However, there is a remarkable stability among meristic characteristics within the species that has persisted essentially in its present form since early postglacial times.
TL;DR: The apparent effect of ethyl chlorophenoxyisobutyrate (CPIB) on serum and tissue lipids of rats was markedly influenced by a terminal period of fasting and/or discontinuation of the drug.
Abstract: The apparent effect of ethyl chlorophenoxyisobutyrate (CPIB) on serum and tissue lipids of rats was markedly influenced by a terminal period of fasting and/or discontinuation of the drug. The significant reduction of serum triglycerides, cholesterol, and phospholipid observed during CPIB administration was no longer present 18 to 24 hours after withdrawal of the drug. The increase in liver triglycerides during CPIB administration was reversed after 24 hours withholding of both food and drug, liver triglycerides then being lower than in fasted control animals.
TL;DR: The effects of sodium chloride, urea, and guanidine hydrochloride, in conjunction with u.v. difference spectra, on various biopolymeric, gelatin complexes are discussed in terms of the electrostatic and hydrogen-bonding forces most probably responsible for specific polymer-gelatin, precipitin-reactions.
TL;DR: Two Morse code operators who could receive code at the rate of 20 words per minute or faster were given training in the reception of 4 and 5 member groups of Morse code characters, presented by means of electrical stimulation of the skin.
Abstract: Two Morse code operators who could receive code at the rate of 20 words per minute or faster were given training in the reception of 4 and 5 member groups of Morse code characters, presented by means of electrical stimulation of the skin. Near the end of the training, one S demonstrated the ability to receive 10 five-character groups per minute with an accuracy of 96%. Results are promising enough to justify further exploration.
TL;DR: In this laboratory, the detection of amylase isozymes has been accomplished by the use of electrophoresis6” and chromatography and principally immunological methods for determining similarities and differences among amylases of a given species (isozymes) and among amyases of different species.
Abstract: The ultimate method for determining the differences among various isozymes would involve their isolation and purification, followed by determinations of their amino acid sequences and perhaps even their secondary and tertiary structures. Since, for mammalian amylases, the only ones isolated, purified, and characterized to any significant extent are hog pancreatic amylase (HPA) and human salivary amylase (HSA), one cannot make such comparisons for amylase isozymes. It has, however, been possible by several methods to detect certain differences among amylases of a given species so that some information is available. In our laboratory we have used principally immunological methods for determining similarities and differences among amylases of a given species (isozymes) and among amylases of different species.’ In other laboratories, the detection of amylase isozymes has been accomplished by the use of electrophoresis6” and chromatography. 6