Showing papers by "University of Virginia published in 1987"
TL;DR: In this article, the entropy-based information criterion (AIC) has been extended in two ways without violating Akaike's main principles: CAIC and CAICF, which make AIC asymptotically consistent and penalize overparameterization more stringently.
Abstract: During the last fifteen years, Akaike's entropy-based Information Criterion (AIC) has had a fundamental impact in statistical model evaluation problems. This paper studies the general theory of the AIC procedure and provides its analytical extensions in two ways without violating Akaike's main principles. These extensions make AIC asymptotically consistent and penalize overparameterization more stringently to pick only the simplest of the ātrueā models. These selection criteria are called CAIC and CAICF. Asymptotic properties of AIC and its extensions are investigated, and empirical performances of these criteria are studied in choosing the correct degree of a polynomial model in two different Monte Carlo experiments under different conditions.
3,850Ā citations
TL;DR: An error grid analysis (EGA) is developed, which describes the clinical accuracy of SMBG systems over the entire range of blood glucose values, taking into account the absolute value of the system-generated glucose value, the relative difference between these two values, and the clinical significance of this difference.
Abstract: Although the scientific literature contains numerous reports of the statistical accuracy of systems for self-monitoring of blood glucose (SMBG), most of these studies determine accuracy in ways that may not be clinically useful. We have developed an error grid analysis (EGA), which describes the clinical accuracy of SMBG systems over the entire range of blood glucose values, taking into account 1) the absolute value of the system-generated glucose value, 2) the absolute value of the reference blood glucose value, 3) the relative difference between these two values, and 4) the clinical significance of this difference. The EGA of accuracy of five different reflectance meters (Eyetone, Dextrometer, Glucometer I, Glucometer II, Memory Glucometer II), a visually interpretable glucose reagent strip (Glucostix), and filter-paper spot glucose determinations is presented. In addition, reanalyses of a laboratory comparison of three reflectance meters (Accucheck II, Glucometer II, Glucoscan 9000) and of two previously published studies comparing the accuracy of five different reflectance meters with EGA is described. EGA provides the practitioner and the researcher with a clinically meaningful method for evaluating the accuracy of blood glucose values generated with various monitoring systems and for analyzing the clinical implications of previously published data.
1,342Ā citations
TL;DR: In this article, a new-product growth model for consumer durables is proposed, which encompasses both diffusion and substitution, and the forecasting properties of the model are demonstrated by estimating parameters over part of the data and projecting shipments for later periods.
Abstract: This study deals with the dynamic sales behavior of successive generations of high-technology products. New technologies diffuse through a population of potential buyers over time. Therefore, diffusion theory models are related to this demand growth. Furthermore, successive generations of a technology compete with earlier ones, and that behavior is the subject of models of technological substitution. Building upon the Bass Bass, F. M. 1969. A new-product growth model for consumer durables. Management Sci.15January 215-227. diffusion model, we develop a model which encompasses both diffusion and substitution. We demonstrate the forecasting properties of the model by estimating parameters over part of the data and projecting shipments for later periods.
942Ā citations
TL;DR: The results indicate that sex and age have independent and interrelated effects on GH secretion, and an amplifying action of estradiol on the neuroendocrine regulation of pulsatile GH release is suggested.
Abstract: We undertook a study of the separate and combined effects of age and sex on the pulsatile pattern of GH secretion. The 24-h secretory profile of GH was generated by 20-min sampling in 10 young women (aged 18-33 yr), 10 young men (aged 18-33 yr), 8 postmenopausal women (aged greater than 55 yr), and 8 older men (aged greater than 55 yr). A computer-assisted pulse analysis program was used to assess both total GH secretion, as reflected in the 24-h integrated GH concentration (IGHC), and pulsatile secretion, as denoted by pulse frequency, duration, amplitude, and the fraction of GH secreted in pulses during the 24-h period (FGHP). IGHC was significantly greater in women than in men (P less than 0.025) and greater in the young than in the old (P less than 0.003). The mean pulse amplitude, duration, and FGHP were each greater in the young (P less than 0.006, P less than 0.03, and P less than 0.0001, respectively), but not significantly different between the sexes. The mean pulse frequency was not affected by sex or age. The serum concentration of free estradiol, but not free testosterone, correlated with IGHC (r = 0.46; P less than 0.005), pulse amplitude (r = 0.53; P less than 0.001), and FGHP (r = 0.59; P less than 0.0002). After correcting for the effects of estradiol, neither sex nor age influenced IGHC or mean pulse amplitude, while the effect of age on FGHP was reduced from 81% to 29%. Of the indices of GH secretion, FGHP had the strongest correlation (r = 0.43; P less than 0.006) with somatomedin-C. Somatomedin-C declined significantly with age in both sexes. Our results indicate that sex and age have independent and interrelated effects on GH secretion. These effects can be largely accounted for by corresponding variations in endogenous estradiol levels. These observations suggest an amplifying action of estradiol on the neuroendocrine regulation of pulsatile GH release.
926Ā citations
TL;DR: In this paper, rates of aqueous, abiotic pyrite oxidation were measured in oxygen-saturated and anaerobic Fe(III)-saturated solutions with initial pH from 2 to 9.
738Ā citations
TL;DR: Observed physiological patterns of fluctuating plasma hormone concentrations can be accounted for by distinct, highly delimited, random bursts of hormone release separated by intervals of secretory quiescence.
Abstract: To investigate patterns of endogenous hormone release, we have proposed a biophysical model in which measured hormone concentrations at any given instant reflect the operation of a suitable cumulation function (secretory input) convolved with an appropriate elimination mechanism (metabolic clearance). The cumulation function underlying a macroscopic hormone secretory burst can be represented by a random (Gaussian) distribution of instantaneous molecular secretory rates, which are centered with some finite and determinable standard deviation about a particular moment in time. The hormone elimination mechanism is described by a mono- or biexponential clearance function. The resultant convolution integral is solved by iterative nonlinear least-squares parameter estimation, in which all plasma hormone concentrations and their variances are considered simultaneously. Experiments with human endocrine time series revealed that the spontaneous secretory patterns of any of multiple distinct anterior pituitary hormones (luteinizing hormone, follicle-stimulating hormone, growth hormone, prolactin, thyrotropin, and adrenocorticotropic hormone) can be described effectively by this parsimonious model. In addition, endogenous hormone disappearance rates determined by deconvolution agreed well with those reported earlier that were determined after exogenous hormone injections. Moreover, this model predicted that durations of underlying secretory impulses are extremely brief; i.e., the standard deviations of the Gaussian distributions of instantaneous secretory rates range from 4.5 min (luteinizing hormone) to 16 min (growth hormone) compared to plasma hormone concentration peaks of 90-140 min in duration. Accordingly, we conclude that observed physiological patterns of fluctuating plasma hormone concentrations can be accounted for by distinct, highly delimited, random bursts of hormone release separated by intervals of secretory quiescence.
546Ā citations
TL;DR: Preliminary reliability and validity data on a psychometric instrument designed to quantify hypoglycemic fear survey are presented, found to have internal consistency and test-retest stability, to covary with elevated glycosylated hemoglobin and to be sensitive to a behavioral treatment program designed to increase awareness of hypoglycemia.
Abstract: Hypoglycemia can lead to various aversive symptomatic, affective, cognitive, physiological, and social consequences, which in turn can lead to the development of possible phobic avoidance behaviors associated with hypoglycemia. On the other hand, some patients may inappropriately deny or disregard warning signs of hypoglycemia. This study presents preliminary reliability and validity data on a psychometric instrument designed to quantify this fear: the hypoglycemic fear survey. The instrument was found to have internal consistency and test-retest stability, to covary with elevated glycosylated hemoglobin, and to be sensitive to a behavioral treatment program designed to increase awareness of hypoglycemia.
516Ā citations
TL;DR: This article found that executives in externally controlled firms receive more compensation for performance and less for scale of operation than executives in internally controlled firms. But, they did not consider the performance of the companies.
Abstract: Using a sample of 71 very large manufacturers, this study demonstrated that executives in externally controlled firms receive more compensation for performance and less for scale of operation than ...
509Ā citations
457Ā citations
TL;DR: The availability of mutations that interrupt biogenic-amine metabolism in an experimentally suitable organism such as Drosophila should provide powerful analytical tools for neurochemists, neurophysiologists, and behavioral biologists.
Abstract: Publisher Summary The genetics of Drosophila provides a number of different approaches toward initiating the investigation of the areas of biogenic-amine metabolism that have previously not been studied or are completely novel to any organism. Biogenic amines are particularly important compounds in insects, for they not only serve as neurotransmitters and modulaters of adenylate cyclase activity in their neurophysiology but also are essential for cross-linking proteins and chitin during sclerotization in the insect cuticle throughout development and especially at times of eclosion (hatching) and molting. A thorough understanding of the regulation of the synthesis, inactivation, and degradation of biogenic amines in the nervous system is mandatory for the elucidation of their roles in the neurophysiology and behavior of any organism. The availability of mutations that interrupt biogenic-amine metabolism in an experimentally suitable organism such as Drosophila should provide powerful analytical tools for neurochemists, neurophysiologists, and behavioral biologists. To facilitate and stimulate research on biogenic amines and sclerotization, this chapter discusses some known facts about the genetics and biochemistry of biogenic amines and sclerotization in Drosophila .
441Ā citations
TL;DR: This study describes the fates of identified 16-cell stage blastomeres and demonstrates that they are distinct and predictable if embryos are preselected for stereotypic cleavages.
TL;DR: The data suggest that fz has two mutably separate functions in establishing hair polarity on the wing, one of which involves the transmittance and/or generation of a polarity signal along the proximal-distal axis of the wing.
Abstract: The function of the frizzled (fz) locus is required for the development of a parallel array of bristles and hairs on the adult cuticle of Drosophila melanogaster. Marked fz mitotic clones from five alleles were generated and examined in the wing. Three alleles have a non-cell-autonomous hair polarity phenotype; wild-type cells distal to fz clones produce hairs that have an abnormal polarity. In contrast, fz clones of the other two fz alleles examined do not disrupt the polarity of neighbouring cells. These data suggest that fz has two mutably separate functions in establishing hair polarity on the wing. One function involves the transmittance and/or generation of a polarity signal along the proximal-distal axis of the wing. The second function involves the cellular interpretation of a polarity signal.
TL;DR: A detailed fate map of all of the progeny derived from each of the blastomeres of the 32-cell-stage South African clawed frog embryo (Xenopus laevis) is presented, which shows the descendants of any one blastomere were distinct and predictable when embryos were preselected for stereotypic cleavages.
TL;DR: This paper examined the historical context which permitted the idea of secularization to go unchallenged for so long, and then developed four discrete types of evidence to account for the present challenge to the theory.
Abstract: The theory of secularization is a product of the social and cultural milieu from which it emerged The expectation of receding religious influence fits well the evolutionary model of modernization Critical reexamination reveals secularization to be an orienting concept grounded in an ideological preference rather than a systematic theory This paper examines the historical context which permitted the idea of secularization to go unchallenged for so long, and then develops four discrete types of evidence to account for the present challenge to the theory Few forecasts have been uttered with more unshakable confidence than sociology's belief that religion is in the midst of its final death throes Writes Gerhard Lenski in the introduction to The Religious Factor in 1961: from its inception [sociology] was committed to the positivist view that religion in the modern world is merely a survival from man's primitive past, and doomed to disappear in an era of science and general enlightenment From the positivist standpoint, religion is, basically, institutionalized ignorance and superstition (p 3)
TL;DR: A gene fusion (the Pcf gene) containing the 5'-flanking and amino-terminal transmembrane segment of the ATP synthase proteolipid gene, parts of the cytochrome oxidase subunit II (coxII) coding region, and the carboxyl terminus and 3-flanking region of an unidentified reading frame (urfS) is revealed.
TL;DR: There appears to be a progressive partial recovery of the normal hair cell counts in the 25- and 32-day-old animals, whereas in the control chicks, there was a 36% hair cell loss.
Abstract: ā¢ This study examines the temporal pattern of hair cell loss in the chick basilar papilla following ten days of gentamicin administration in hatchling chicks. Chicks were subsequently killed at ages 11, 18, 25, and 32 days. The basilar papillae were embedded in plastic and serially sectioned for light microscopic analysis. Hair cell counts were obtained at 100-Ī¼m intervals throughout the length of the papilla. Significant hair cell loss was documented basally in the 11-day-old chicks, and spread apically over time to maximal loss in the 18-day-old animals. Relative to the control chicks, there was a 36% hair cell loss in these animals. Interestingly, there appears to be a progressive partial recovery of the normal hair cell counts in the 25- and 32-day-old animals. ( Arch Otolaryngol Head Neck Surg 1987;113:1058-1062)
TL;DR: The augmentation in GH secretion that occurs during either spontaneous puberty or exogenous testosterone therapy is an amplitude-modulated phenomenon, relatively independent of changes in pulse frequency.
Abstract: The augmentation of GH secretion that occurs during puberty has been attributed to changes in sex steroid levels that enhance the frequency and amplitude of GH pulses. To investigate the specific GH pulse characteristics responsible for such augmentation we analyzed the serum GH concentration profiles of 10 boys in Tanner stages I-II of sexual development (group A; aged 10 5/12-15 1/12 yr) and compared their GH pulse characteristics with those of 5 boys at Tanner stages IV-V of development (group B; aged 14 8/12-15 1/12 yr). We also reanalyzed previously reported data from 5 prepubertal boys (group C; aged 13 6/12-15 5/12 yr) before and after 10 weeks of treatment with testosterone enanthate (100 mg/4 weeks, im). Using a pulse detection algorithm that constrains the false positive pulse detection rate to less than 5% (Cluster), we found that group B boys had a significantly higher mean serum GH pulse amplitude compared to group A boys (17.1 +/- 2.6 vs. 8.6 +/- 1.7 ng/mL; P = 0.012), but both groups had the same mean GH pulse frequency (group B, 5.4 +/- 0.5 pulses/24 h vs. group A, 5.5 +/- 0.4 pulses/24 h; P greater than 0.05). Similar changes were found in group C boys before and after testosterone therapy; there was no significant change in GH pulse frequency (6.6 +/- 0.9 before vs. 7.6 +/- 0.5 pulses/24 h after treatment; P greater than 0.05), but there was a significant increase in the GH pulse amplitude after therapy (6.8 +/- 1.6 before vs. 15.4 +/- 2.4 ng/mL after treatment; P = 0.04). When the 24-h GH concentration profiles were analyzed using a mathematically distinct method for the estimation of pulse amplitudes, namely the Fourier expansion time series, we confirmed a significant increase in GH pulse amplitude with later stages of puberty and androgen treatment. We conclude that the augmentation in GH secretion that occurs during either spontaneous puberty or exogenous testosterone therapy is an amplitude-modulated phenomenon, relatively independent of changes in pulse frequency. Such an effect may be secondary to the action of sex steroid hormones modulating either the responsivity of somatotrophs to endogenous GH-releasing hormone, the amount of GH-releasing hormone secreted, or the tonic inhibitory tone of somatostatin.
TL;DR: The results demonstrate that large seasonal variations in allergen can occur in dust from all sites and are not restricted to the houses of allergic patients, and suggest that mite-allergic patients are more likely to have attacks in the fall at a time when their houses have greater than 10 micrograms AgP1Eq per gram of dust.
Abstract: In order to study seasonal variation in dust-mite allergen, we obtained dust samples from bedding, carpet, and/or sofas in 12 houses in central Virginia, monthly, for 1 year. The houses included those of nine patients with asthma of whom six were allergic to dust mites. Dust samples were assayed with an inhibition radioimmunoassay for mite allergen that detects cross-reacting determinants on Der f and Der p I from Dermatophagoides farinae and D. pteronyssinus, respectively. The results are expressed as micrograms of antigen P1 equivalent (AgP1Eq). The results demonstrate that large seasonal variations in allergen, i.e., more than twentyfold, can occur in dust from all sites and are not restricted to the houses of allergic patients. However, dust from some sites, particularly sofas, remained "high" (greater than 10 micrograms AgP1Eq per gram), whereas dust from other sites remained "low" (less than 1 microgram AgP1Eq per gram) throughout the year. Levels of mite allergen generally started to rise in July about 1 month after the rise in humidity. In August to December, the mean levels of AgP1Eq in house dust were highly significantly increased relative to April to May. In keeping with this finding, in 31 of 37 sites, the highest level for the year was observed in August through December. In four sites, mite bodies were counted, and the numbers increased sharply in June to July; however, they decreased in September in parallel with falls in humidity but several months before the fall in mite allergen. Ryegrass-pollen allergen in 12 sites was also assayed in house dust, and pollen-allergen levels demonstrated a sharp increase in May or June that fell back to preseason values within 2 months. Dust was also obtained from the houses of 50 patients with acute or severe asthma. The results on these samples suggest that mite-allergic patients are more likely to have attacks in the fall at a time when their houses have greater than 10 micrograms AgP1Eq per gram of dust. The magnitude of changes observed seasonally within individual houses and of differences between houses within a close geographic area suggests that interpretation of the relationship between allergic symptoms and mite-allergen exposure will require measurement of mite-allergen levels in individual houses.
TL;DR: The biochemical mechanisms of the in vitro interaction between rat and human colonic mucins and axenic E. histolytica trophozoites are studied to prevent amebic attachment to and cytolysis of host epithelial cells.
Abstract: Establishment of adherence by Entamoeba histolytica is mediated by a 170-kD Gal/GalNAc inhibitable lectin and is required for cytolysis and phagocytosis of mammalian target cells. We studied the biochemical mechanisms of the in vitro interaction between rat and human colonic mucins and axenic E. histolytica trophozoites. Crude mucus prevented amebic adherence to Chinese hamster ovary (CHO) cells by up to 70%. Purification of the colonic mucins by Sepharose 4B chromatography, nuclease digestion, and cesium chloride gradient centrifugation resulted in a 1,000-fold enrichment of the inhibitory mucins. Purified rat mucin inhibited amebic adherence to and cytolysis of homologous rat colonic epithelial cells. Oxidation and enzymatic cleavage of rat mucin Gal and GalNAc residues completely abrogated mucin inhibition of amebic adherence. The binding of rat 125I-mucin to amebae was galactose specific, saturable, reversible, and pH dependent. A monoclonal antibody specific for the 170-kD amebic Gal/GalNAc lectin completely inhibited the binding of rat 125I-mucin. Rat mucin bound to Affigel affinity purified the amebic lectin from conditioned medium. Colonic mucin glycoproteins act as an important host defense by binding to the parasite's adherence lectin, thus preventing amebic attachment to and cytolysis of host epithelial cells.
TL;DR: DSM-III diagnoses were applied to 26 monozygotic and 34 dizygotic probands and their co-twins from the Maudsley Hospital schizophrenic series of Gottesman and Shields and both affective disorder and schizophrenia were found in genetically identical individuals.
Abstract: DSM-III diagnoses were applied to 26 monozygotic (MZ) and 34 dizygotic (DZ) probands and their co-twins from the Maudsley Hospital (1948 to 1965) schizophrenic series of Gottesman and Shields. DSM-III criteria for schizophrenia were found to be highly reliable and valid, and to have a broad heritability of 0.85, which is comparable with the Research Diagnostic Criteria and Feighner criteria from which they were derived. When the full range of DSM-III diagnoses were considered, both affective disorder and schizophrenia were found in genetically identical individuals. The effect of DSM-III nosology on the twin series was also explored by adding other diagnoses to that of schizophrenia and observing the effect on the MZ/DZ concordance ratio. The addition of affective disorder with mood-incongruent delusions to the schizophrenia spectrum produced the largest increase in the ratio and, by implication, a "more genetic" combination than schizophrenia alone. The maximum MZ/DZ concordance ratio (7.68) was produced by schizophrenia, plus affective disorder with mood-incongruent delusions, plus schizotypal personality disorder, plus atypical psychosis. The effect of adding paranoid disorder (paranoia) and all other affective categories was a reduction in the ratio.
TL;DR: The authors examined the role of monetary policy in the early stages of the Great Depression and considered the mechanism whereby this policy may have affected real activity, concluding that the depression was preceded by a dramatic shift towards a highly contractionary monetary policy.
TL;DR: The data support the interpretation that the IGL plays a significant role in relaying information regarding illu mination intensity to the SCN, and modify the change in period of the free-running activity rhythm produced by changing the level of constant light.
Abstract: Photic signals affect circadian activity rhythms by both phasic and tonic mechanisms that modulate pacemaker phase and period. In mammals, the effects of light on circadian activity are mediated by the retina, which communicates with the suprahiasmatic nucleus (SCN) by two different anatomical routes: the retino-hypothalamic tract (RHT), originating in the retina, and the geniculo-hypothalamic tract (GHT), arising from a retino-recipient nucleus, the intergeniculate leaflet (IGL). We assessed the roles of these two afferent systems in mediating phasic and tonic effects of light on circadian activity in IGL-lesioned animals. Destruction of the IGL significantly affected phase shifts produced by brief light pulses (phasic effect) and modified the change in period (tau) of the free-running activity rhythm produced by changing the level of constant light (LL) (tonic effect). Phase advances produced by brief light pulses were decreased in amplitude while phase delays were increased in IGL-lesioned animals as compared to controls. The free-running period in constant dark (tau DD) of IGL-lesioned animals was greater than tau DD of controls, and the lengthening of tau normally produced by LL was not observed or was greatly reduced in IGL-lesioned animals. Entrainment to light-dark cycles was unaffected by the lesions, as were other aspects of the circadian activity rhythm that normally change in response to LL (e.g., activity-rest ratio, total activity, splitting). Our data support the interpretation that the IGL plays a significant role in relaying information regarding illumination intensity to the SCN.
TL;DR: Purified lectin competitively inhibited amebic adherence to target cells by binding to receptors on the target Chinese hamster ovary cells in a Gal-inhibitable manner.
Abstract: Entamoeba histolytica adheres to human colonic mucus, colonic epithelial cells, and other target cells via a galactose (Gal) or N-acetyl-D-galactosamine (GalNAc) inhibitable surface lectin Blockade of this adherence lectin with Gal or GalNAc in vitro prevents amebic killing of target cells We have identified and purified the adherence lectin by two methods: affinity columns derivatized with galactose monomers or galactose terminal glycoproteins, and affinity columns and immunoblots prepared with monoclonal antibodies that inhibit amebic adherence By both methods the adherence lectin was identified as a 170-kD secreted and membrane-bound amebic protein The surface location of the lectin was confirmed by indirect immunofluorescence Purified lectin competitively inhibited amebic adherence to target cells by binding to receptors on the target Chinese hamster ovary cells in a Gal-inhibitable manner
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TL;DR: A placement algorithm, Genie, is presented for the assignment of modules to locations on chips, an adaptation of the genetic algorithm technique that has traditionally been a tool of the artificial intelligence community.
Abstract: A placement algorithm, Genie, is presented for the assignment of modules to locations on chips. Genie is an adaptation of the genetic algorithm technique that has traditionally been a tool of the artificial intelligence community. The technique is a paradigm for examining a state space. It produces its solutions through the simultaneous consideration and manipulation of a set of possible solutions. The manipulations resemble the mechanics of natural evolution. For example, solutions are "mated" to produce "offspring" solutions. Genie has been extensively run on a variety of small test instances. Its solutions were observed to be quite good and in several cases optimal.
TL;DR: In this article, the supraspinal afferent and efferent connections of the A5 noradrenergic cell group were examined in rats and very small deposits of HRP-WGA were made in the rostral A5 area.
Abstract: The supraspinal afferent and efferent connections of the A5 noradrenergic cell group were examined in rats. Very small deposits of HRP-WGA were made in the rostral A5 area. Catecholamine histofluorescence techniques were used to confirm that the deposits overlapped the A5 column. Retrogradely labeled cells were present in the perifornical area and paraventricular nucleus of the hypothalamus, the Kolliker-Fuse nucleus, dorsal parabrachial area, intermediate and caudal portions of the nucleus of the solitary tract, and the ventral medullary reticular formation in the areas of the A1 and B1 cell groups. Anterograde HRP-WGA labeling was found in several areas of the subcortical CNS. The contribution of A5 neurons to this labeling was confirmed with retrogradely transported fluorescent latex microspheres combined with catecholamine histofluorescence techniques. The A5 cell group was found to have significant projections to the central nucleus of the amygdala, perifornical area of the hypothalamus, midbrain periaqueductal gray, parabrachial area, and the nucleus of the solitary tract. Other A5 projections include the paraventricular nucleus of the thalamus, the bed nucleus of the stria terminalis, and possibly the zona incerta and lateral and dorsal hypothalamic areas. In addition, A5 neurons may innervate the ventrolateral reticular formation of the medulla. Virtually all of the areas innervated by A5 noradrenergic neurons are involved in cardiovascular regulation. In addition, the A5 area receives afferent input from major cardiovascular regulatory centers of the supraspinal CNS. Thus the A5 cell group has the potential to exert a significant influence on the cardiovascular regulatory system.
TL;DR: The results support previous evidence that baroreceptor primary afferents may release a glutamate-like transmitter in the NTS and indicate that a similar type of excitatory transmitter is involved at the level of the ventrolateral medulla in mediating or modulating both vagal and sympathetic baroreflexes.
TL;DR: In this article, strong empirical evidence links deposition of strong acids from the atmosphere to acidification of freshwaters and loss offish populations and the widespread recent acidification in eastern North America and Europe is due to the superposition of acid deposition upon natural acidifying processes in soils.
Abstract: Strong empirical evidence links deposition of strong acids from the atmosphere to acidification of freshwaters and loss offish populations. Chemical processes in soils explain the composition of soil solution and surface waters and when coupled with input-output fluxes these processes, in concert with acid deposition, account for observed trends in soil and water acidification. The widespread recent acidification of surface water in eastern North America and Europe is due to the superposition of acid deposition upon natural acidifying processes in soils.
TL;DR: Preliminary laboratory studies suggest that currents between 2 and 50 cm sā1 affect leaf production of Zostera marina L. under light-saturated conditions and canopy modification of flow structure and light capture efficiency by the deflected canopy should be examined.
TL;DR: The name "desmoplastic infantile ganglioglioma" is proposed for this apparently distinct clinicopathological entity, whose massive size is indicative of a pre- or perinatal origin.
Abstract: ā Eleven cases of supratentorial neuroepithelial tumor presenting in infancy are reported. The tumors were characterized by their voluminous size, their intense desmoplasia, and the frequent presence of divergent astrocytic and ganglionic differentiation as demonstrated by special neurohistological and immunohisto- and immunocytochemical techniques. All the tumors presented in subjects below the age of 18 months, usually within the first 4 months of life. They most often involved the frontal and parietal regions and were composed predominantly of a dense desmoplastic tissue superficially resembling a moderately cellular fibroma. The fibroblastic elements were admixed with variable numbers of pleomorphic neuroepithelial cells. Divergent astrocytic and neuronal differentiation was demonstrable in nine of the 11 tumors. All showed astrocytic differentiation. The study of one example by electron microscopy, immunocytochemistry, and tissue culture disclosed that the astrocytic tumor cells were partly invested ...
TL;DR: In this article, the effects of four modes of political participation (voting, campaigning, peaceful protest, and aggressive behavior) on two fundamental attitudes, political efficacy and regime stability, are explored.
Abstract: This paper explores the effects of four modes of political participation--voting, campaigning, peaceful protest, and aggressive behavior--on two fundamental attitudes, political efficacy and regime...