Showing papers by "Cornell University published in 1991"
TL;DR: In addition to NDF, new improved methods for total dietary fiber and nonstarch polysaccharides including pectin and beta-glucans now are available and are also of interest in rumen fermentation.
23,302 citations
TL;DR: This book make understandable the cluster analysis is based notion of starsmodern treatment, which efficiently finds accurate clusters in data and discusses various types of study the user set explicitly but also proposes another.
Abstract: The Wiley-Interscience Paperback Series consists of selected books that have been made more accessible to consumers in an effort to increase In both the increasingly important and distribution we show how these methods. Our experiments demonstrate that together can deal with most applications technometrics. In an appropriate visualization technique is to these new. The well written and efficiently finds accurate clusters in data including. Of applied value for several preprocessing tasks discontinuity preserving smoothing feature clusters! However the model based notion of domain knowledge from real data repositories in data. Discusses various types of study the user set explicitly but also propose another. This book make understandable the cluster analysis is based notion of starsmodern treatment.
7,423 citations
TL;DR: A wine-loving economist we know purchased some nice Bordeaux wines years ago at low prices as discussed by the authors, but would neither be willing to sell the wine at the auction price nor buy an additional bottle at that price.
Abstract: A wine-loving economist we know purchased some nice Bordeaux wines years ago at low prices. The wines have greatly appreciated in value, so that a bottle that cost only $10 when purchased would now fetch $200 at auction. This economist now drinks some of this wine occasionally, but would neither be willing to sell the wine at the auction price nor buy an additional bottle at that price. Thaler (1980) called this pattern—the fact that people often demand much more to give up an object than they would be willing to pay to acquire it—the endowment effect. The example also illustrates what Samuelson and Zeckhauser (1988) call a status quo bias, a preference for the current state that biases the economist against both buying and selling his wine. These anomalies are a manifestation of an asymmetry of value that Kahneman and Tversky (1984) call loss aversion—the disutility of giving up an object is greater that the utility associated with acquiring it. This column documents the evidence supporting endowment effects and status quo biases, and discusses their relation to loss aversion.
4,025 citations
TL;DR: In this paper, the authors examine both how the biogeochemistry of the nitrogen cycle could cause limitation to develop, and how nitrogen limitation could persist as a consequence of processes that prevent or reduce nitrogen fixation.
Abstract: The widespread occurrence of nitrogen limitation to net primary production in terrestrial and marine ecosystems is something of a puzzle; it would seem that nitrogen fixers should have a substantial competitive advantage wherever nitrogen is limiting, and that their activity in turn should reverse limitation. Nevertheless, there is substantial evidence that nitrogen limits net primary production much of the time in most terrestrial biomes and many marine ecosystems. We examine both how the biogeochemistry of the nitrogen cycle could cause limitation to develop, and how nitrogen limitation could persist as a consequence of processes that prevent or reduce nitrogen fixation. Biogeochemical mechansism that favor nitrogen limitation include: A number of mechanisms could keep nitrogen fixation from reversing nitrogen limitation. These include: The possible importance of these and other processes is discussed for a wide range of terrestrial, freshwater, and marine ecosystems.
3,332 citations
TL;DR: This survey identified several horticultural crops in a variety of families with genomes only two or three times as large asArabidopsis and several fruit trees (a pricot, cherry, mango, orange, papaya, and peach) that should facilitate molecular studies of these crops.
Abstract: Nuclear DNA contents of more than 100 important plant species were measured by flow cytometry of isolated nuclei stained with propidium iodide.Arabidopsis exhibits developmentally regulated multiploidy and has a 2C nuclear DNA content of 0.30 pg (145 Mbp/1C), twice the value usually cited. The 2C value for rice is only about three times that ofArabidopsis. Tomato has a 2C value of about 2.0 pg, larger than commonly cited. This survey identified several horticultural crops in a variety of families with genomes only two or three times as large asArabidopsis; these include several fruit trees (a pricot, cherry, mango, orange, papaya, and peach). The small genome sizes of rice and the horticultural plants should facilitate molecular studies of these crops.
2,930 citations
Journal Article•
TL;DR: Constitutive generation of large amounts of reactive oxygen intermediates, if it occurs in vivo, might contribute to the ability of some tumors to mutate, inhibit antiproteases, injure local tissues, and therefore promote tumor heterogeneity, invasion, and metastasis.
Abstract: Few nonphagocytic cells are known to generate reactive oxygen intermediates. Based on horseradish peroxidase-dependent, catalase-inhibitable oxidation of fluorescent scopoletin, seven human tumor cell lines constitutively elaborated H2O2 at rates (up to 0.5 nmol/10(4) cells/h) large enough that cumulative amounts at 4 h were comparable to the amount of H2O2 produced by phorbol ester-triggered neutrophils. Superoxide dismutase-inhibitable ferricytochrome c reduction was detectable at much lower rates. H2O2 production was inhibited by diphenyleneiodonium, a flavoprotein binder (concentration producing 50% inhibition, 0.3 microM), and diethyldithiocarbamate, a divalent cation chelator (concentration producing 50% inhibition, 3 microM), but not by cyanide or azide, inhibitors of electron transport, or by agents that inhibit xanthine oxidase, polyamine oxidase, or cytochrome P450. Cytochrome b559, present in human phagocytes and lymphocytes, was undetectable in these tumor cells by a sensitive spectrophotometric method. Mouse fibroblasts transfected with human tyrosinase complementary DNA made melanin, but not H2O2. Constitutive generation of large amounts of reactive oxygen intermediates, if it occurs in vivo, might contribute to the ability of some tumors to mutate, inhibit antiproteases, injure local tissues, and therefore promote tumor heterogeneity, invasion, and metastasis.
2,417 citations
TL;DR: In this paper, an endogenous growth model with multiple assets is developed, and the effects of introducing financial intermediation into this environment are considered, and conditions are provided under which the introduction of intermediaries shifts the composition of savings toward capital, causing intermediation to be growth promoting.
Abstract: An endogenous growth model with multiple assets is developed. Agents who face random future liquidity needs accumulate capital and a liquid, but unproductive asset. The effects of introducing financial intermediation into this environment are considered. Conditions are provided under which the introduction of intermediaries shifts the composition of savings toward capital, causing intermediation to be growth promoting. In addition, intermediaries generally reduce socially unnecessary capital liquidation, again tending to promote growth.
2,184 citations
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TL;DR: Applications of a density-functional theory of nonuniform fluid mixtures to the fluid-solid transition of simple binary mixtures of hard spheres demonstrates the importance of relative atomic sizes in determining lattice constants and suggests that for sufficiently small disparities in atomic size Vegard's law may also hold along the fluid -solid coexistence curve.
Abstract: Vegard's law is an approximate empirical rule which holds that a linear relation exists, at constant temperature, between the crystal lattice constant of an alloy and the concentrations of the constituent elements. Applications of a density-functional theory of nonuniform fluid mixtures to the fluid-solid transition of simple binary mixtures of hard spheres demonstrates the importance of relative atomic sizes in determining lattice constants and suggests that for sufficiently small disparities in atomic size Vegard's law may also hold along the fluid-solid coexistence curve.
2,000 citations
TL;DR: It is suggested that synthesis of NO mediates much of the antimicrobial activity of mouse macrophages against some fungal, helminthic, protozoal and bacterial pathogens.
1,507 citations
TL;DR: Affinity cross-linking and equilibrium binding experiments with 125I-labeled NGF indicate that p140prototrk binds NGF specifically in cultured cells with a dissociation constant of 10(-9) molar.
Abstract: The trk proto-oncogene encodes a 140-kilodalton, membrane-spanning protein tyrosine kinase (p140prototrk) that is expressed only in neural tissues. Nerve growth factor (NGF) stimulates phosphorylation of p140prototrk in neural cell lines and in embryonic dorsal root ganglia. Affinity cross-linking and equilibrium binding experiments with 125I-labeled NGF indicate that p140prototrk binds NGF specifically in cultured cells with a dissociation constant of 10(-9) molar. The identification of p140prototrk as an NGF receptor indicates that this protein participates in the primary signal transduction mechanism of NGF.
1,393 citations
TL;DR: This thermostable enzyme, DNA ligase, is harnessed in the assay reported here that both amplifies DNA and discriminates a single-base substitution, and was exploited to detect 200 target molecules as well as to discriminate between normal beta A- and sickle beta S- globin genotypes from 10-microliters blood samples.
Abstract: Polymerase chain reaction, using thermostable DNA polymerase, has revolutionized DNA diagnostics. Another thermostable enzyme, DNA ligase, is harnessed in the assay reported here that both amplifies DNA and discriminates a single-base substitution. This cloned enzyme specifically links two adjacent oligonucleotides when hybridized at 65 degrees C to a complementary target only when the nucleotides are perfectly base-paired at the junction. Oligonucleotide products are exponentially amplified by thermal cycling of the ligation reaction in the presence of a second set of adjacent oligonucleotides, complementary to the first set and the target. A single-base mismatch prevents ligation/amplification and is thus distinguished. This method was exploited to detect 200 target molecules as well as to discriminate between normal beta A- and sickle beta S- globin genotypes from 10-microliters blood samples.
TL;DR: Reconstitution experiments reveal a new growth factor receptor-mediated mechanism of cellular differentiation involving trk and the low-affinity NGF receptor and the tyrosine kinase trk gene product.
Abstract: Nerve growth factor (NGF) interacts with two different low-affinity receptors that can be distinguished by affinity crosslinking Reconstitution experiments by membrane fusion and transient transfection into heterologous cells indicate that high-affinity NGF binding requires coexpression and binding to both the low-affinity NGF receptor and the tyrosine kinase trk gene product These studies reveal a new growth factor receptor-mediated mechanism of cellular differentiation involving trk and the low-affinity NGF receptor
TL;DR: In this article, the authors showed that the IL-10 was exceedingly potent at suppressing the ability of mouse peritoneal macrophages (m phi) to release tumor necrosis factor alpha (TNF-alpha).
Abstract: Recombinant mouse interleukin 10 (IL-10) was exceedingly potent at suppressing the ability of mouse peritoneal macrophages (m phi) to release tumor necrosis factor alpha (TNF-alpha). The IC50 of IL-10 for the suppression of TNF-alpha release induced by 0.5 microgram/ml lipopolysaccharide was 0.04 +/- 0.03 U/ml, with as little as 1 U/ml suppressing TNF-alpha production by a factor of 21.4 +/- 2.5. At 10 U/ml, IL-10 markedly suppressed m phi release of reactive oxygen intermediates (ROI) (IC50 3.7 +/- 1.8 U/ml), but only weakly inhibited m phi release of reactive nitrogen intermediates (RNI). Since TNF-alpha is a T cell growth and differentiation factor, whereas ROI and RNI are known to inhibit lymphocyte function, it is possible that m phi exposed to low concentrations of IL-10 suppress lymphocytes. m phi deactivated by higher concentrations of IL-10 might be permissive for the growth of microbial pathogens and tumor cells, as TNF-alpha, ROI, and RNI are major antimicrobial and tumoricidal products of m phi. IL-10's effects on m phi overlap with but are distinct from the effects of the two previously described cytokines that suppress the function of mouse m phi, transforming growth factor beta and macrophage deactivation factor. Based on results with neutralizing antibodies, all three m phi suppressor factors appear to act independently.
TL;DR: This poster presents a probabilistic procedure to constrain the number of particles in the response of the immune system to the presence of Tau.
Abstract: The ISIS toolkit is a distributed programming environment based on support for virtually synchronous process groups and group communication. A suite of protocols is presented to support this model. The approach revolves around a multicast primitive, called CBCAST, which implements a fault-tolerant, causally ordered message delivery. This primitive can be used directly or extended into a totally ordered multicast primitive, called ABCAST. It normally delivers messages immediately upon reception, and imposes a space overhead proportional to the size of the groups to which the sender belongs, usually a small number. It is concluded that process groups and group communication can achieve performance and scaling comparable to that of a raw message transport layer. This finding contradicts the widespread concern that this style of distributed computing may be unacceptably costly.
TL;DR: In this paper, the collision dynamics of a liquid droplet on a solid metallic surface were studied using a flash photographic method, which provided clear images of the droplet structure during the deformation process.
Abstract: The collision dynamics of a liquid droplet on a solid metallic surface were studied using a flash photographic method. The intent was to provide clear images of the droplet structure during the deformation process. The ambient pressure (0.101 MPa), surface material (polished stainless steel), initial droplet diameter (about 1.5 mm), liquid (n-heptane) and impact Weber number (43) were fixed. The primary parameter was the surface temperature, which ranged from 24 degrees C to above the Leidenfrost temperature of the liquid. Experiments were also performed on a droplet impacting a surface on which there existed a liquid film created by deposition of a prior droplet. The evolution of wetted area and spreading rate, both of a droplet on a stainless steel surface and of a droplet spreading over a thin liquid film, were found to be independent of surface temperature during the early period of impact. This result was attributed to negligible surface tension and viscous effects, and in consequence the measurements made during the early period of the impact process were in good agreement with previously published analyses which neglected these effects. A single bubble was observed to form within the droplet during impact at low temperatures. As surface temperature was increased the population of bubbles within the droplet also increased because of progressive activation of nucleation sites on the stainless steel surface. At surface temperatures near to the boiling point of heptane, a spoke-like cellular structure in the liquid was created during the spreading process by coalescence of a ring of bubbles that had formed within the droplet. At higher temperatures, but below the Leidenfrost point, numerous bubbles appeared within the droplet, yet the overall droplet shape, particularly in the early stages of impact (< 0.8 ms), was unaffected by the presence of these bubbles. The maximum value of the diameter of liquid which spreads on the surface is shown to agree with predictions from a simplified model.
Book•
01 Jan 1991TL;DR: Gilovich argues that the biases and stereotypes that help us process an overload of complex information inevitably distort what we would like to believe is reality as discussed by the authors, and that awareness of our propensity to make these systematic errors is the first step to more effective analysis and action.
Abstract: When can we trust what we believe - that "teams and players have winning streaks", that "flattery works", or that "the more people who agree, the more likely they are to be right" - and when are such beliefs suspect? Thomas Gilovich offers a guide to the fallacy of the obvious in everyday life. Illustrating his points with examples, and supporting them with the latest research findings, he documents the cognitive, social and motivational processes that distort our thoughts, beliefs, judgements and decisions. In a rapidly changing world, the biases and stereotypes that help us process an overload of complex information inevitably distort what we would like to believe is reality. Awareness of our propensity to make these systematic errors, Gilovich argues, is the first step to more effective analysis and action.
TL;DR: Therapeutic approaches are proposed in which normal cells may be selectively protected against toxic antitumor agents and radiation by cysteine- and glutathione-delivery compounds.
TL;DR: The results suggested that, for a trait with low heritability (soluble solids), the phenotype of F3 progeny could be predicted more accurately from the genotype of the F2 parent at QTLs than from the phenotypic variation of theF2 individual.
Abstract: As part of ongoing studies regarding the genetic basis of quantitative variation in phenotype, we have determined the chromosomal locations of quantitative trait loci (QTLs) affecting fruit size, soluble solids concentration, and pH, in a cross between the domestic tomato (Lycopersicon esculentum Mill.) and a closely-related wild species, L. cheesmanii. Using a RFLP map of the tomato genome, we compared the inheritance patterns of polymorphisms in 350 F2 individuals with phenotypes scored in three different ways: (1) from the F2 progeny themselves, grown near Davis, California; (2) from F3 families obtained by selfing each F2 individual, grown near Gilroy, California (F3-CA); and (3) from equivalent F3 families grown near Rehovot, Israel (F3-IS). Maximum likelihood methods were used to estimate the approximate chromosomal locations, phenotypic effects (both additive effects and dominance deviations), and gene action of QTLs underlying phenotypic variation in each of these three environments. A total of 29 putative QTLs were detected in the three environments. These QTLs were distributed over 11 of the 12 chromosomes, accounted for 4.7-42.0% of the phenotypic variance in a trait, and showed different types of gene action. Among these 29 QTLs, 4 were detected in all three environments, 10 in two environments, and 15 in only a single environment. The two California environments were most similar, sharing 11/25 (44%) QTLs, while the Israel environment was quite different, sharing 7/20 (35%) and 5/26 (19%) QTLs with the respective California environments. One major goal of QTL mapping is to predict, with maximum accuracy, which individuals will produce progeny showing particular phenotypes. Traditionally, the phenotype of an individual alone has been used to predict the phenotype of its progeny. Our results suggested that, for a trait with low heritability (soluble solids), the phenotype of F3 progeny could be predicted more accurately from the genotype of the F2 parent at QTLs than from the phenotype of the F2 individual. For a trait with intermediate heritability (fruit pH), QTL genotype and observed phenotype were about equally effective at predicting progeny phenotype. For a trait with high heritability (mass per fruit), knowing the QTL genotype of an individual added little if any predictive value, to simply knowing the phenotype. The QTLs mapped in the L. esculentum X L. cheesmanii F2 appear to be at similar locations to many of those mapped in a previous cross with a different wild tomato (L. chmielewskii).(ABSTRACT TRUNCATED AT 400 WORDS)
TL;DR: Gel filtration chromatography indicated that the induced NO synthase was catalytically competent as a dimer of approximately 250 kDa but could be dissociated into inactive monomers of approximately 130 kDa in the absence of L-arginine, FAD, and tetrahydrobiopterin.
Abstract: A soluble nitric oxide (NO) synthase activity was purified 426-fold from a mouse macrophage cell line activated with interferon gamma and bacterial lipopolysaccharide by sequential anion-exchange, affinity, and gel filtration chromatography. SDS/PAGE of the purified NO synthase gave three closely spaced silver-staining protein bands between 125 and 135 kDa. When assayed in the presence of L-arginine, NADPH, tetrahydrobiopterin, FAD, and reduced thiol, purified NO synthase had a specific activity of 1313 nmol of NO2- plus NO3- per min per mg. The apparent Km of the enzyme for L-arginine and NADPH was 2.8 and 0.3 microM, respectively. Addition of calcium ions with or without calmodulin did not increase the activity of the purified enzyme, and NO synthesis was not altered by calmodulin inhibitors. Gel filtration chromatography indicated that the induced NO synthase was catalytically competent as a dimer of approximately 250 kDa but could be dissociated into inactive monomers of approximately 130 kDa in the absence of L-arginine, FAD, and tetrahydrobiopterin. Upon heat denaturation, NO synthase released 1.1 mol of FAD and 0.55 mol of FMN per mol of 130-kDa subunit. Thus, inducible macrophage NO synthase differs in several respects from constitutive NO synthases and is one of very few eukaryotic enzymes containing both FAD and FMN.
TL;DR: This article found that much of the causal pathway between IQ and schooling points in the direction of the importance of the quantity of schooling one attains (highest grade successfully completed), which fosters the development of cognitive processes that underpin performance on most IQ tests.
Abstract: This is a review of the relationship between schooling, IQ, and the cognitive processes presumed to underpin IQ. The data suggest that much of the causal pathway between IQ and schooling points in the direction of the importance of the quantity of schooling one attains (highest grade successfully completed). Schooling fosters the development of cognitive processes that underpin performance on most IQ tests. In western nations, schooling conveys this influence on IQ and cognition through practices that appear unrelated to systematic variation in quality of schools. If correct, this could have implications for the meaning one attaches to IQ in screening and prediction as well as for efforts to influence the development of IQ through changes in schooling practices
[...]
TL;DR: New evidence is summarized that the response of cells to cytokines can be markedly affected by the extracellular matrix in which most cells are normally embedded.
01 Jan 1991
TL;DR: The method is used to isolate total genomic DNA (nuclear, chloroplast, and mitochondrial) and is a rapid, inexpensive method that is suitabie for use in conjunction with other protocois, such as isolation of DNA enriched for cpDNA.
Abstract: This procedure has been used with success on a wide variety of plant groups and even some animals. The method is used to isolate total genomic DNA (nuclear, chloroplast, and mitochondrial). It is a rapid, inexpensive method that is suitabie for use in conjunction with other protocois, such as isolation of DNA enriched for cpDNA. it is also easy to scale down for use in population sampling, using 0.01g or less of fresh tissue. Other applications include isolation of DNA from herbarium specimens (Doyle & Dickson, 1987. Taxon 36:715–722), and isolation of RNA. A brief word on the history of the protocol is in order. This procedure was modified by us (Doyle and Doyle, 1987. Phytochemical Bulletin 19:11–15) for use with fresh plant tissue from a method of Saghai-Maroof et al. (1984, PNAS USA 81:8014–8019) who used lyophilized tissue. They in turn had developed their procedure from earlier protocols. We were recently asked to publish a slightly modified version of our procedure (Doyle and Doyle, 1990 Focus 12:13–15). We recently learned from Brian Taylor (Texas A&M University, USA) that he had published a virtually identical procedure for fresh tissue, also in Focus, in 1982 (Taylor & Powell, Focus 4:4–6) of which we (and apparently the editors of Focus!) were entirely unaware. It is indeed a useful procedure, thus independently confirmed.
TL;DR: These analyses provide both a relatively non-destructive method for assessing water sources of plants and a means of assessing potential competitive interactions among cooccurring taxa, and may aid in resolving the role of water in determining plant distributions in areas characterized by sharp soil moisture gradients.
Abstract: A LONG-STANDING axiom is that plant distribution is strongly influenced by soil moisture content1,2. While it has been shown that plant taxa inhabiting streamside communities receive or use more water3, it is assumed that this water is obtained from the stream adjacent to where they are found growing. Here we show, using hydrogen isotope ratio analyses at natural abundance levels, that mature streamside trees growing in or directly next to a perennial stream used little or none of the surface stream water. The deuterium to hydrogen content of both source and xylem waters indicated that mature trees were using waters from deeper strata. Although adult trees may have roots distributed continuously throughout a soil profile, it seemed that the most active sites of water absorbtion were limited to deeper soil layers. In contrast, small streamside individuals appeared to use stream water, whereas small non-streamside individuals used recent precipitation as their primary water source. Our analyses provide both a relatively non-destructive method for assessing water sources of plants and a means of assessing potential competitive interactions among cooccurring taxa. In addition, the method may aid in resolving the role of water in determining plant distributions in areas characterized by sharp soil moisture gradients.
TL;DR: A method for comparing polygons that is a metric, invariant under translation, rotation, and change of scale, reasonably easy to compute, and intuitive is presented.
Abstract: A method for comparing polygons that is a metric, invariant under translation, rotation, and change of scale, reasonably easy to compute, and intuitive is presented. The method is based on the L/sub 2/ distance between the turning functions of the two polygons. It works for both convex and nonconvex polygons and runs in time O(mn log mn), where m is the number of vertices in one polygon and n is the number of vertices in the other. Some examples showing that the method produces answers that are intuitively reasonable are presented. >
15 Jul 1991
TL;DR: A finitary axiomatization of the algebra of regular events involving only equations and equational implications that is sound for all interpretations over Kleene algebras is given.
Abstract: A finitary axiomatization of the algebra of regular events involving only equations and equational implications that is sound for all interpretations over Kleene algebras is given. Axioms for Kleene algebra are presented, and some basic consequences are derived. Matrices over a Kleene algebra are considered. The notion of an automaton over an arbitrary Kleen algebra is defined and used to derive the classical results of the theory of finite automata as a result of the axioms. The completeness of the axioms for the algebra of regular events is treated. Open problems are indicated. >
TL;DR: The S receptor kinase (SRK) gene is described, a previously uncharacterized gene that resides at the S locus that exhibits striking homology to the secreted product of the S-locus glycoprotein (SLG) gene.
Abstract: Self-recognition between pollen and stigma during pollination in Brassica oleracea is genetically controlled by the multiallelic self-incompatibility locus (S). We describe the S receptor kinase (SRK) gene, a previously uncharacterized gene that resides at the S locus. The nucleotide sequences of genomic DNA and of cDNAs corresponding to SRK predict a putative transmembrane receptor having serine/threonine-specific protein kinase activity. Its extracellular domain exhibits striking homology to the secreted product of the S-locus glycoprotein (SLG) gene and is connected via a single pass transmembrane domain to a protein kinase catalytic center. SRK alleles derived from different S-locus genotypes are highly polymorphic and have apparently evolved in unison with genetically linked alleles of SLG. SRK directs the synthesis of several alternative transcripts, which potentially encode different protein products, and these transcripts were detected exclusively in reproductive organs. The identification of SRK may provide new perspectives into the signal transduction mechanism underlying pollen recognition.
TL;DR: The text analysis problem is examined, and modern approaches leading to the identification and retrieval of selected text items in response to search requests are discussed.
Abstract: Recent developments in the storage, retrieval, and manipulation of large text files are described. The text analysis problem is examined, and modern approaches leading to the identification and retrieval of selected text items in response to search requests are discussed.
01 Jul 1991
TL;DR: A new general reflectance model for computer graphics is presented and provides a smooth transition from diffuse-like to specular reflection as the wavelength and incidence angle are increased or the surface roughness is decreased.
Abstract: A new general reflectance model for computer graphics is presented. The model is based on physical optics and describes specular, directional diffuse, and uniform diffuse reflection by a surface. The reflected light pattern depends on wavelength, incidence angle, two surface roughness parameters, and surface refractive index. The formulation is self consistent in terms of polarization, surface roughness, masking/shadowing, and energy. The model applies to a wide range of materials and surface finishes and provides a smooth transition from diffuse-like to specular reflection as the wavelength and incidence angle are increased or the surface roughness is decreased. The model is analytic and suitable for Computer Graphics applications. Predicted reflectance distributions compare favorably with experiment. The model is applied to metallic, nonmetallic, and plastic materials, with smooth and rough surfaces.
TL;DR: In this article, the authors compared a more traditional, unmediated model of work-based role stress and its consequences on job satisfaction and burnout to two models in which the role stress-affective work outcome relationship is mediated by work-home conflict across two samples of public sector professionals: engineers and nurses.
Abstract: Using structural equation modeling, this paper compares a more traditional, unmediated model of work-based role stress and its consequences on job satisfaction and burnout to two models in which the role stress-affective work outcome relationship is mediated (partially and completely) by work-home conflict across two samples of public sector professionals: engineers and nurses. The findings indicate that a model in which role conflict and overload have both direct and indirect effects—via work-home conflict—on job burnout and satisfaction (‘Partial Mediation’ model) achieves a better overall ‘fit’ than two alternative models. Furthermore, the findings suggest that while the two groups perceive many aspects of the work-home relationship differently, for both groups, work-based role conflict is an important antecedent of work-home conflict, and increased burnout an important direct consequence of work-home conflict. Finally, on the basis of the findings, the authors conclude that perspectives which view the work and non-work realms as independent must be reconsidered, and that the nature of the work-home relationship may, to a great extent, be contingent upon the way different occupational groups perceive their work situations.
TL;DR: Recent work showing that anatomical networks in the nervous system provide a physical back bone upon which a large library of modulatory inputs can operate allows the networks to produce multiple variations in output under different conditions.
Abstract: All animals need to shape their behavior to the demands posed by their internal and external environments. Our goal is to understand how modu lation of the neural networks that generate behavior occurs, so that animals can change their behavior when necessary. We discuss recent work showing that anatomical networks in the nervous system provide a physical back bone upon which a large library of modulatory inputs can operate. These allow the networks to produce multiple variations in output under different conditions. In the scope of this review, it is impossible to discuss all the neural circuits in which modulatory processes are now known to shape behavior (for reviews, see Selverston 1985, Harris-Warrick 1988, Kravitz 1988, Getting 1989, Bicker & Menzel 1989, Marder & Altman 1989). Instead, we have chosen examples from the literature to highlight general principles and new findings that have arisen from recent work in this field. We emphasize simple rhythmic behaviors, because more is known concerning their neural circuitry than for complex, nonrepetitive actions. As research continues, we anticipate that ideas first developed in simpler invertebrate nervous systems will be found to apply to more complex vertebrate preparations.