Showing papers by "University of Iowa published in 1981"
TL;DR: In this paper, the SPR Board provides recommendations for publishing data on electrodermal activity (EDA) and a short outline of principles for EDA measurement is given, and recommendations from an earlier report (Fowles et al., ) are incorporated.
Abstract: This committee was appointed by the SPR Board to provide recommendations for publishing data on electrodermal activity (EDA). They are intended to be a stand-alone source for newcomers and experienced users. A short outline of principles for electrodermal measurement is given, and recommendations from an earlier report (Fowles et al., ) are incorporated. Three fundamental techniques of EDA recording are described: (1) endosomatic recording without the application of an external current, (2) exosomatic recording with direct current (the most widely applied methodology), and (3) exosomatic recording with alternating current-to date infrequently used but a promising future methodology. In addition to EDA recording in laboratories, ambulatory recording has become an emerging technique. Specific problems that come with this recording of EDA in the field are discussed, as are those emerging from recording EDA within a magnetic field (e.g., fMRI). Recommendations for the details that should be mentioned in publications of EDA methods and results are provided.
1,609 citations
TL;DR: The inversely-nonlinear relationship of muscle contraction force and the possible contraction duration is utilized in a method to mathematically predict individual muscle forces and shows substantial agreement with that activity pattern predicted when endurance is used as the optimization criterion.
1,275 citations
TL;DR: Total effects on turnover were found to be the greatest for four determinants: intent to stay, opportunity, general training, and job satisfaction.
Abstract: Longitudinal data on 1,091 registered nurses in seven hospitals were used to estimate a causal model of turnover in organizations. Total effects on turnover were found to be the greatest for four d...
1,079 citations
TL;DR: MUELLER and PARCEL as mentioned in this paper argue that it is ill-advised to use impressionistic or outdated measures of SES in psychological research and propose two occupation-based measures, the Duncan Socioeconomic Index and the Siegel Prestige Scale, as the best measures of the SES of individuals or household heads.
Abstract: MUELLER, CHARLES W., and PARCEL, TOBY L. Measures of Socioeconomic Status: Alternatives and Recommendations. CHILD DEVELOPMENT, 1981, 52, 13-30. In this paper we argue that it is ill-advised to use impressionistic or outdated measures of SES in psychological research. After we critique such inappropriate measures, 2 occupation-based measures, the Duncan Socioeconomic Index and the Siegel Prestige Scale, are recommended as the best measures of the SES of individuals or household heads. Another strategy is described for measuring household or family SES where the household characteristics and composition vary.
523 citations
TL;DR: In this article, measurements from the Lepedea plasma instruments and the flux gate magnetometers on ISEE 1 and 2 are used to examine the nature of the hydromagnetic waves associated with the various classes of ions backstreaming from the earth's bow shock.
Abstract: Measurements from the Lepedea plasma instruments and the flux gate magnetometers on ISEE 1 and 2 are used to examine the nature of the hydromagnetic waves associated with the various classes of ions backstreaming from the earth's bow shock. The reflected ions, which are confined to a narrow energy and angular range, are accompanied by small amplitude (less than approximately 1/2 gamma peak to peak) left-handed waves at frequencies close to 1 Hz in the spacecraft frame. Diffuse backstreaming particles with a broad energy spectrum are associated with low frequency (approximately 30-s period), large amplitude (approximately 5 gamma peak to peak) waves. Intermediate particles are associated with a mixture of these two wave types. Often the waves associated with the diffuse beams steepen as if they were minishocks. The leading edge (trailing edge in the spacecraft frame) frequently appears to break up into a whistler mode wave packet. These discrete wave packets are right-hand polarized and have frequencies from below the proton gyrofrequency to well above it in the plasma frame and are blown back towards the earth by the solar wind.
463 citations
TL;DR: The problems of research design and execution in studies of diagnostic reliability are reviewed, and statistical problems are examined, and solutions to many of these problems are suggested, including recommendations of appropriate reliability coefficients and data analyses.
Abstract: • The existing literature on the reliability of psychiatric diagnosis falls into two periods, the earlier reporting low reliability and the latter reporting much higher figures. The reasons for this trend are examined in the context of a discussion of the design of diagnostic reliability studies. The problems of research design and execution in studies of diagnostic reliability are reviewed, and statistical problems are examined. Solutions to many of these problems are suggested, including recommendations of appropriate reliability coefficients and data analyses.
440 citations
TL;DR: It is concluded that adrenergic inputs to the paraventricular nucleus may influence cells that project to the median eminence and to preganglionic autonomic cell groups in the medulla and spinal cord.
Abstract: The distribution of catecholaminergic fibers and cell bodies in the paraventricular and supraoptic nuclei of the hypothalamus was investigated with immunohistochemical methods in the adult albino rat. Sections through the nuclei were stained with antisera to the catecholamine synthesizing enzymes tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (DBH), and phenylethanolamine-N-methyltransferase (PNMT). The results suggest that adrenergic (PNMT-stained) fibers innervate the entire parvocellular division of the paraventricular nucleus, although the highest density of fibers was found in the medial part of the division. Only widely scattered adrenergic fibers are found in the magnocellular division of the nucleus and in the supraoptic nucleus. Noradrenergic fibers appear to innervate the periventricular zone of the paraventricular nucleus and those parts of the paraventricular and supraoptic nuclei that contain predominantly vasopressinergic neurons in both the normal and in the homozygous Brattleboro rat. Significant numbers--somewhat more than 500--of dopaminergic (TH-stained) neurons are found in the paraventricular nucleus; the cells are distributed throughout the nucleus but are concentrated in the medial and periventricular parts of the parvocellular division. Double-labeling experiments with the retrogradely transported tracer true blue indicate that between 4% and 8% of the dopaminergic neurons in the paraventricular nucleus project to the region of the dorsal vagal complex and/or thoracic levels of the spinal cord. It is concluded that adrenergic inputs to the paraventricular nucleus may influence cells that project to the median eminence and to preganglionic autonomic cell groups in the medulla and spinal cord. Noradrenergic inputs to the supraoptic and paraventricular nuclei may influence primarily vasopressinergic cells that project to the posterior lobe of the pituitary, as well as cells in the periventricular part of the paraventricular nucleus that project to the median eminence.
374 citations
TL;DR: Miniaturized probes using 1-mm-diameter piezoelectric crystals that emit a 20-mHz signal and receive the reflected sound waves from passing blood cells are constructed to measure changes in regional blood flow and vascular resistance in a conscious freely moving rat.
Abstract: Development of techniques for the continuous measurement of regional blood flow and vascular resistance in intact small animals has been impeded primarily by the bulkiness of flow probes. The avail...
345 citations
TL;DR: In this article, the authors presented detailed in situ observations from the ISEE 3 spacecraft of energetic electrons, plasma waves, and radio emission for the type III solar radio burst of 1979 February 17.
Abstract: We present detailed in situ observations from the ISEE 3 spacecraft of energetic electrons, plasma waves, and radio emission for the type III solar radio burst of 1979 February 17. The reduced one-dimensional distribution function f (v) of the electrons is constructed as a function of time. Since the faster electrons arrive before the slower ones, a bump on tail distribution is formed which is unstable on the growth of Langmuir waves. The plasma wave growth computed from f (v) agrees well with the observed onset of the Langmuir waves, and there is qualitative agreement between variations in the plasma wave levels and in the development of regions of positive slope in f (v). The evolution of f (v), however, predicts far higher plasma wave levels than those observed. The maximum levels observed are about equal to the threshold for nonlinear wave processes, such as oscillating two-stream instability and soliton collapse. Also, the lack of obvious plateauing of the distribution suggests that the observed waves have been removed from resonance with the beam electrons. Finally, the plasma waves are observed to be highly impulsive in nature.
333 citations
TL;DR: Rats exposed to ethanol throughout their gestation were found to have abnormally distributed mossy fibers in temporal regions of the hippocampus, demonstrating that prenatal exposure to ethanol causes alterations in neuronal circuitry that persist to maturity.
Abstract: Rats exposed to ethanol throughout their gestation were found to have abnormally distributed mossy fibers in temporal regions of the hippocampus. This demonstrates that prenatal exposure to ethanol causes alterations in neuronal circuitry that persist to maturity. Such defects may play a role in the mental retardation often observed in children with fetal alcohol syndrome.
287 citations
TL;DR: Methods for the estimation of genetic correlations from inbred strain comparisons are presented and appear to be valid when compared to those derived from more demanding parent-offspring comparisons and to correlated responses to selection.
Abstract: Genetic correlations measure the extent of pleiotropic effects of polygenes on pairs of characters or the closeness of linkage between sets of loci influencing the traits and held in allelic (gametic) disequilibrium. Their importance for research lies primarily in predicting correlated responses of one trait to selection based on values for another, and secondarily in analyzing the complex organization of biological systems. Genetic correlations appear to limit the rate and set the direction of multivariate evolution. In view of this, efficient methods for estimating genetic correlations may be essential for understanding the role of behavior in adaptation and for predicting behavioral change in evolution. In this paper we present methods for the estimation of genetic correlations from inbred strain comparisons. Estimates from inbred strains are relatively easy to obtain and appear to be valid when compared to those derived from more demanding parent-offspring comparisons and to correlated responses to selection.
TL;DR: The present paper unifies two studies of linear programming problems for which the greedy algorithm works, and establishes the converse of each theorem.
TL;DR: A region of diminished plasma density has been found to occur at the source of auroral kilometric radiation (AKR) at 70 deg + or - 3 deg invariant magnetic latitude as discussed by the authors.
Abstract: A region of diminished plasma density has been found to occur at the source of auroral kilometric radiation (AKR). The density within this auroral plasma cavity, determined from limited Hawkeye wave data, was less than 1/cu cm from 1.8 to 3 earth radii geocentric, at 70 deg + or - 3 deg invariant magnetic latitude. The altitude variation of the magnetic field produces a minimum in the ratio of plasma frequency to cyclotron frequency within the cavity which accounts for the observed spectrum of AKR.
TL;DR: It is reported that treatment of pituitary cells with ergocryptine leads to rapid inhibition of prolactin gene transcription and that addition of monobutyryl cyclic AMP to ergOCryptine-pretreated cells results in a rapid stimulation of Prolactin genes transcription.
Abstract: A large body of evidence suggests that the synthesis1,2 and secretion3–7 of the pituitary hormone prolactin is inhibited by the hypothalamic hormone dopamine. The finding that dopamine inhibits adenylate cyclase activity of rat pituitary8 and human prolactin-secreting adenoma9 suggests that the dopaminergic inhibition of prolactin synthesis may be mediated by decreased levels of cyclic AMP. Recently, the dopaminergic inhibition of prolactin synthesis has been shown to involve decreased concentrations of prolactin mRNA2,10. Furthermore, monobutyryl cyclic AMP increases prolactin mRNA levels in pituitary cells treated with the potent dopaminergic agonist ergocryptine11. Such changes in prolactin mRNA levels could involve transcriptional or post-transcriptional events. Here we report that treatment of pituitary cells with ergocryptine leads to rapid inhibition of prolactin gene transcription and that addition of monobutyryl cyclic AMP to ergocryptine-pretreated cells results in a rapid stimulation of prolactin gene transcription.
TL;DR: It is hypothesized that consistent differences in seed size could result in dramatic differences in dispersal, and hence reproduction, over the lifetime of individual trees.
Abstract: We observed birds and mammals visiting individual plants in a Panamanian population of the rainforest tree Virola surinamensis ("Wild Nutmeg") to determine (1) relative importance of different dispersal agents, and (2) the relationships between crop size, crop quality, and seed removal. Arils of this tree are exceptionally nutritious (63% fat, 9% nonstructural carbohydrate, 3% protein), but draw remarkably few species of fruit-eating animals. Six birds take 77% of the seeds handled by animals. One toucan (Ramphastos swainsonii) accounts for 35% of the seeds handled; other birds (Penelope purpurascens, Trogon massena, Baryphthengus martii, Pteroglossus torquatus, Ram- phastos sulfuratus) play lesser roles. The smallest visitor, a cotinga (Tityra semifasciata) eats arils but does not disperse seeds. One monkey (Ateles geoffroyi) removes 3% of the seeds handled by frugivores, but smells and rejects or otherwise wastes 9%. Such a small assemblage is anomalous in a forest with at least 78 species of fruit-eating animals; other trees with arillate seeds of similar size draw as many as 23 frugivores. We hypothesize that the size of the assemblage is limited by seed size, small crop size, and perhaps by defensive compounds in the arils. Despite the small assemblage, an average of 62% (range: 13-91%) of the fruits available to animals are taken. Fruits are so nutritious that trees with both small and large crops are depleted; no variance in the percentage of seeds removed can be attributed to crop size. Fruits of different individual trees do vary in size; 59% of the variation in the percentage of seeds taken can be attributed to mean seed size. Fruit-eating animals preferentially deplete trees with small seeds, and coincidentally favor trees with high aril-to-seed ratios. No significant portion of the variance in "dispersal success" can be explained by aril mass alone. We hypothesize that consistent differences in seed size could result in dramatic differences in dispersal, and hence reproduction, over the lifetime of individual trees. On the other hand, selection may alternatively favor small seed size and high dispersability in years when frugivores are abundant, and large seed size and enhanced seedling vigor in the parental stand when fruit-eating birds are scarce. Small-seeded plants are likely to colonize new sites; large-seeded individuals are likely to produce offspring that fare well in competition with other seedlings near parent trees.
TL;DR: Kinesiologic analysis of the gaits of 21 autistic, 15 normal, and five hyperactive-aggressive children revealed that the autistic patients had reduced stride lengths, increased stance times, and decreased knee extension and ankle dorsiflexion at ground contact.
Abstract: • Kinesiologic analysis of the gaits of 21 autistic, 15 normal, and five hyperactive-aggressive children revealed that the autistic patients had (a) reduced stride lengths, (b) increased stance times, (c) increased hip flexion at "toe-off," and (d) decreased knee extension and ankle dorsiflexion at ground contact. In many respects, the gait differences between the autistic and normal subjects resembled differences between the gaits of parkinsonian patients and of normal adults. These preliminary results are compatible with the view that the autistic syndrome may be associated with specific dysfunction of the motor system affecting, among other structures, the basal ganglia.
TL;DR: The timing of mass losses of females may be adaptive by permitting a 23% reduction in power required to remain aloft in flight before the most demanding period of feeding nestlings.
Abstract: Losses of mass in breeding passerines are commonly observed and presumed to reflect physiological stress from activity while feeding nestlings. Analyses of changes of body mass in House Wrens (Troglodxvtes aedon) show that: (1) females lose ==13% of their body mass between onset of incubation and fledging, but reattain their original mass for second broods; (2) 50% of mass loss is achieved before hatching is completed; (3) loss of mass is virtually complete before food demands of the nestlings are greatest; (4) change in body mass during the period of highest food demand is independent of brood size; (5) males foraging at rates similar to females show no change in mass. These patterns do not reflect stress. Rather, the timing of mass losses of females may be adaptive by permitting a 23% reduction in power required to remain aloft in flight before the most demanding period of feeding nestlings.
TL;DR: The results showed a significant familial clustering of cognitive disabilities in the siblings of autistic probands, which included disturbances in expressive and receptive language, specific learning disabilities, and varying degrees of mental subnormality.
Abstract: Individual components of cognitive disability were assessed in the siblings of 41 autistic probands and compared with similar measures from a control group of siblings of Down's syndrome individuals. The results showed a significant familial clustering of cognitive disabilities in the siblings of autistic probands. These cognitive impairments included disturbances in expressive and receptive language, specific learning disabilities, and varying degrees of mental subnormality.
TL;DR: The findings are interpreted as providing limited support for the hypothesis that normal aging does not necessarily involve a general decline in level of cognitive functioning.
Abstract: As part of a study of dementia, 162 normal volunteers in the age range of 65–84 years were given a battery of nine neuropsychological tests assessing temporal orientation, short-term memory, language functions, and visuoperceptive capacity. When compared to subjects less than 65 years of age, the group showed little evidence of generalized decline in cognitive function before the age of 80 years. The 80–84 years subgroup showed a higher overall failure rate on the tests than the younger subgroups. Nevertheless, 70% of the subjects in the 80–84 years subgroup made no more than one failure on the nine tests. There were substantial differences among the tests in respect to their sensitivity to the effects of aging. The largest decline in performance was shown on tests of short-term visual memory, serial digit learning, and facial recognition. The other verbal, memory, and visuoperceptive tests were performed well up to the age of 80 years. The findings are interpreted as providing limited support fo...
TL;DR: It is concluded that it is possible to make lifetime diagnoses reliably in a nonpatient population when the Schedule for Affective Disorders and Schizophrenia-Lifetime Version and Research Diagnostic Criteria were used to interview ill and well relatives of probands in the National Institute of Mental Health Collaborative Study of the Psychobiology of Depression.
Abstract: It is important to determine the reliability of lifetime diagnosis in a nonpatient population, for this type of diagnostic data and this type of sample are used in many genetic, epidemiological, and nosological studies. We examined the reliability of lifetime diagnosis when the Schedule for Affective Disorders and Schizophrenia-Lifetime Version and Research Diagnostic Criteria were used to interview ill and well relatives of probands in the National Institute of Mental Health Collaborative Study of the Psychobiology of Depression. Subjects were interviewed three times, so data are available concerning both short- and long-interval test-retest reliability. Short-interval test-retest reliability was excellent for both diagnoses and symptoms. Reliability was also quite high in the long-interval test-retest study. We conclude that it is possible to make lifetime diagnoses reliably in a nonpatient population.
01 Aug 1981-International Journal of Human-computer Studies \/ International Journal of Man-machine Studies
TL;DR: An extension and refinement of the author's theory for human visual information processing is presented, which is then applied to the problem of human facial recognition, and pertains to Gestalt recognition of any class of familiar objects or scenes.
Abstract: This paper presents an extension and refinement of the author's theory for human visual information processing, which is then applied to the problem of human facial recognition. Several fundamental processes are implicated: encoding of visual images into neural patterns, detection of simple facial features, size standardization, reduction of the neural patterns in dimensionality, and finally correlation of the resulting sequence of patterns with all visual patterns already stored in memory. In the theory presented here, this entire process is automatically "driven" by the storage system in what amounts to an hypothesis verification paradigm. Neural networks for carrying out these processes are presented and syndromes resulting from damage to the proposed system are analyzed. A correspondence between system component and brain anatomy is suggested, with particular emphasis on the role of the primary visual cortex in this process. The correspondence is supported by structural and electrophysiological properties of the primary visual cortex and other related structures. The logical (computational) role suggested for the primary visual cortex has several components: size standardization, size reduction, and object extraction. The result of processing by the primary visual cortex, it is suggested, is a neural encoding of the visual pattern at a size suitable for storage. (In this context, object extraction is the isolation of regions in the visual field having the same color, texture, or spatial extent.) It is shown in detail how the topology of the mapping from retina to cortex, the connections between retina, lateral geniculate bodies and primary visual cortex, and the local structure of the cortex itself may combine to encode the visual patterns. Aspects of this theory are illustrated graphically with human faces as the primary stimulus. However, the theory is not limited to facial recognition but pertains to Gestalt recognition of any class of familiar objects or scenes.
TL;DR: In this article, three dominant types of plasma waves are observed which are associated with energetic particle streams coming from the bow shock: ion acoustic waves, electron plasma oscillations, and whistler mode waves.
Abstract: Plasma wave and plasma data from ISEE 1 and 2 are examined. In the upstream solar wind, three dominant types of plasma waves are observed which are associated with energetic particle streams coming from the bow shock: ion acoustic waves, electron plasma oscillations, and whistler mode waves. The ion acoustic waves occur simultaneously with either ion beams or a dispersed ion population in the energy range from 0.5 to greater than 45 keV. The electron plasma oscillations are long-wavelength, nearly monochromatic electrostatic waves which are closely correlated with the flux of low-energy electrons, especially in the 0.2-1.5 keV range. Electromagnetic waves with frequencies below 200 Hz are observed when either ion beams or dispersed ion distributions are present; for these waves the refractive index determined from the wave B to E ratio is consistent with whistler mode radiation.
TL;DR: Musculoskeletal data suitable for use in biomechanical analyses of hip function are presented by marking the approximate locations of hip muscle attachment points on the bony pelvis and right femur of an adult, male, dry bone specimen.
TL;DR: The corticopontine projections of the cingulate cortices were investigated in the rhesus monkey with the use of autoradiography and a well-organized topography of projections was observed.
TL;DR: The Voyager 1 plasma wave instrument detected many familiar types of plasma waves during the encounter with Saturn, including ion-acoustic waves and electron plasma oscillations upstream of the bow shock, an intense burst of electrostatic noise at the shock, and chorus, hiss, electrostatic electron cyclotron waves, and upper hybrid resonance emissions in the inner magnetosphere.
Abstract: The Voyager 1 plasma wave instrument detected many familiar types of plasma waves during the encounter with Saturn, including ion-acoustic waves and electron plasma oscillations upstream of the bow shock, an intense burst of electrostatic noise at the shock, and chorus, hiss, electrostatic electron cyclotron waves, and upper hybrid resonance emissions in the inner magnetosphere. A clocklike Saturn rotational control of low-frequency radio emissions was observed, and evidence was obtained of possible control by the moon Dione. Strong plasma wave emissions were detected at the Titan encounter indicating the presence of a turbulent sheath extending around Titan, and upper hybrid resonance measurements of the electron density show the existence of a dense plume of plasma being carried downstream of Titan by the interaction with the rapidly rotating magnetosphere of Saturn.
TL;DR: There was a significantly greater proportion of autistic girls than boys with IQs less than 50 and with evidence of brain damage and the implication of sex differences in the possible mode of familial transmission of autism is discussed.
Abstract: There are studies suggesting possible hereditary influence in autism. Data on 102 autistic children, 78 boys and 24 girls, showed that there was a significantly greater proportion of autistic girls than boys with IQs less than 50 and with evidence of brain damage. The autistic girls also had a greater proportion of relatives affected with autism or cognitive-language deficit than did the boys. The implication of sex differences in the possible mode of familial transmission of autism is discussed.
01 Dec 1981
TL;DR: In this article, the instrumentation for obtaining global images of the auroral oval from the high-altitude spacecraft of the Dynamics Explorer Mission is described, and it is noted that the three spin-scan auroral imaging photometers are expected to be able to effectively view the dim emissions from earth in the presence of strong stray light sources near their fields-of-view along the sunlit portion of the spacecraft orbit.
Abstract: The instrumentation for obtaining global images of the auroral oval from the high-altitude spacecraft of the Dynamics Explorer Mission is described. It is noted that the three spin-scan auroral imaging photometers are expected to be able to effectively view the dim emissions from earth in the presence of strong stray light sources near their fields-of-view along the sunlit portion of the spacecraft orbit. A special optical design that includes an off-axis parabolic mirror as the focusing element and super-reflecting mirror surfaces is used to minimize the effects of stray light. The rotation of the spacecraft and an instrument scanning mirror provide the two-dimensional array of pixels making up an image frame. It is pointed out that the full width of the fields-of-view of the photometers corresponding to a single pixel is 0.29 deg and that the angular dimensions of a typical full frame are 30 deg x 30 deg and span 14,400 pixels.
TL;DR: The hypothesis that P/O's are inversely related to 1) the likelihood of a pollen grain reaching a stigma and 2) pollen grain size is tested.
Abstract: The initial work on pollen-ovule ratios (P/O's) was predicated on the assumption that P/O's reflected the efficiency of pollination; the more efficient the transfer of pollen, the lower the P/O (Cruden, 1977). The observation that P/O's decrease in switches from xenogamy (cross-pollination) to autogamy (self-pollination) and autogamy to cleistogamy, without loss of fecundity is consistent with the initial assumption (Cruden, 1977). Additional support for the efficiency argument was provided by Cruden and Jensen (1979) who showed that species in Onagraceae have very low P/O's compared to species in other families with equivalent breeding systems and fecundities. Viscin threads, which hold pollen grains together in large clumps, and quite large stigmas contribute to the efficient transport and transfer of pollen in Onagraceae. The observation that xenogamous species with low P/O's (e.g., in Epilobium, Geranium and Mirabilis) have large pollen grains and those with high P/O's (various Boraginaceae) have quite small pollen grains suggested that P/O's might reflect pollen grain size, as well as number. Because pollen grain germination and penetration of the stigmatic surface by the pollen tube are a function of pollen number (Brewbaker and Majumder, 1961; Jennings and Topham, 1971) and products stored in the intine (Stanley and Linskens, 1974; Heslop-Harrison, 1975) we reasoned, with respect to germination and the contribution of gametes to successful fertilizations, that the individual pollen grains of species with large pollen grains must be more successful than the individual pollen grains of species with small pollen grains. The data presented below were gathered to test the hypothesis that P/O's are inversely related to 1) the likelihood of a pollen grain reaching a stigma and 2) pollen grain size. First, we present the underlying assumptions of our hypothesis and examine our data. Second, we discuss information in the literature on distylous species which provide an independent test of the hypothesis. We also comment briefly on resource allocation to male sexual function, a possible trade-off between pollen number and pollen grain size, and P/O's as indicators of breeding systems.
TL;DR: In situ dental amalgams can increase the level of mercury in expired air, and examined subjects with dental amalgAMS had higher pre-chewing mercury levels in their expired air than those without amalgams.
Abstract: The expired air of a group of 48 persons, 40 with and eight without dental amalgam restorations, was analyzed for its mercury content before and after chewing. Expired air samples were collected in polyethylene bags, and a known quantity of each was pumped into the mercury detector for measurement. The results showed that examined subjects with dental amalgams had higher pre-chewing mercury levels in their expired air than those without amalgams. After chewing, these levels were increased an average of 15.6-fold in the former and remained unchanged in the latter group. It was concluded that in situ dental amalgams can increase the level of mercury in expired air.