Showing papers by "Michigan State University published in 1992"

Camera calibration with distortion models and accuracy evaluation

Abstract: A camera model that accounts for major sources of camera distortion, namely, radial, decentering, and thin prism distortions is presented. The proposed calibration procedure consists of two steps: (1) the calibration parameters are estimated using a closed-form solution based on a distribution-free camera model; and (2) the parameters estimated in the first step are improved iteratively through a nonlinear optimization, taking into account camera distortions. According to minimum variance estimation, the objective function to be minimized is the mean-square discrepancy between the observed image points and their inferred image projections computed with the estimated calibration parameters. The authors introduce a type of measure that can be used to directly evaluate the performance of calibration and compare calibrations among different systems. The validity and performance of the calibration procedure are tested with both synthetic data and real images taken by tele- and wide-angle lenses. >

Oxygen activation and the conservation of energy in cell respiration.

Abstract: Many of the membrane-associated oxidases that catalyse respiratory reduction of O2 to water simultaneously couple this exergonic reaction to the translocation of protons across the inner mitochondrial membrane, or the cell membrane in prokaryotes, a process by which metabolic energy is conserved for subsequent synthesis of ATP. The molecular mechanism of O2 reduction and its linkage to H+ translocation are now emerging. The bimetallic haem iron-copper reaction centre in this family of enzymes is the critical structure for catalysis of both these processes.

The turn model for adaptive routing

Abstract: We present a model for designing wormhole routing algorithms that are deadlock free, livelock free, minimal or nonminimal, and maximally adaptive. A unique feature of this model is that it is not based on adding physical or virtual channels to network topologies (though it can be applied to networks with extra channels). Instead, the model is based on analyzing the directions in which packets can turn in a network and the cycles that the turns can form. Prohibiting just enough turns to break all of the cycles produces routing algorithms that are deadlock free, livelock free, minimal or nonminimal, and maximally adaptive for the network. In this paper, we focus on the two most common network topologies for wormhole routing, n-dimensional mesh, just a quarter of the turns must be prohibited to prevent deadlock. The remaining three quarters of the turns permit partial adaptiveness in routing. Partially adaptive routing algorithms are described for 2D meshes, n-dimensional meshes, k-ary n-cubes, and hypercubes. Simulations of partially adaptive and nonadaptive routing algorithms for 2D meshes and hypercubes show that which algorithm has the lowest latencies and highest sustainable throughput depends on the pattern of message traffic. For nonuniform traffic, partially adaptive routing algorithms perform better than non-adaptive ones.

Lm tests for a unit root in the presence of deterministic trends

Abstract: This paper provides a new unit root test based on an alternative parameterization which has previously been considered by Bhargava (1986). This parameterization allows for trend under both the null and the alternative, without introducing any parameters that are irrelevant under either. This is not so in the Dickey-Fuller parameterizations. The new test is extracted from the score or LM principle under the assumption that the errors are iid N(0, sigma squared (epsilon)), but our asymptotics hold under more general assumptions about the errors. Two forms of the test (a coefficient test and at t-test) are derived.

Teachers' beliefs about teaching and learning: A constructivist perspective.

Abstract: Teachers are viewed as important agents of change in the reform effort currently under way in education and thus are expected to play a key role in changing schools and classrooms. Paradoxically, however, teachers are also viewed as major obstacles to change because of their adherence to outmoded forms of instruction that emphasize factual and procedural knowledge at the expense of deeper levels of understanding. New constructivist approaches to teaching and learning, which many reformers advocate, are inconsistent with much of what teachers believe--a problem that may be overcome if teachers are willing to rethink their views on a number of issues. This article seeks to advance this cause by identifying important aspects of current thinking that may get in the way of teachers adopting a constructivist approach to teaching and learning.

The caregiver reaction assessment (CRA) for caregivers to persons with chronic physical and mental impairments

Abstract: The development and testing of a multidimensional instrument to assess the reactions of family members caring for elderly persons with physical impairments, Alzheimer's disease, and cancer is reported Forty items were administered to a sample of 377 caregivers of persons with physical impairments and Alzheimer's disease Five dimensions of caregivers' reactions were identified through exploratory factor analysis Using confirmatory factor analysis on an independent sample (N = 377), these dimensions were tested for factorial invariance across spouse and nonspouse caregivers and between caregivers of persons with cancer and those caring for persons with Alzheimer's disease The subscales also had a high level of factorial invariance across a three-wave panel study (N = 185) The subscales appeared consistent with first order tests of construct validity

Output feedback stabilization of fully linearizable systems

Abstract: An observer-based controller is designed to stabilize a fully linearizable nonlinear system. The system is assumed to be left-invertible and minimum-phase. The controller is robust to uncertainties in modelling the nonlinearities of the system. The design of the controller and the stability analysis employs the techniques of singular perturbations. A new ‘Tikhonov-like’ theorem is presented and used to analyse the system when the control is globally bounded.

Accumulation of yolk proteins in insect oocytes

Abstract: In insects, accumulation of yolk, or vitellogenesis, is a heterosynthetic pro­ cess, in which an extraovarian tissue, the fat body, produces yolk protein precursors ( 1 , 92). Heterosynthetic vitellogenesis occurs even in the most primitive insects, the Apterygota (9, 10, 1 13). Only for two apterygote insects have ultrastructural observations indicated participation of autosynthesis in vitellogensis (9, 10) . This claim, however, requires confirmation by biochem­ ical or immunochemical means . Because of the heterosynthetic nature of vitellogenesis in insects, their oocytes are highly specialized for the specific accumulation of extraovarian yolk protein precursors . Telfer first implicated the role of endocytosis in yolk deposition in insect oocytes . He found selective concentration of some hemolymph-borne proteins in yolk bodies of Hyalophora cecropia oocytes ( 1 29, 1 3 1 ) . Coated vesicles, the cellular structures associated with selective endocytosis, were first observed in oocytes of the mosquito Aedes aegypti ( 1 1 2) . These pioneering studies were followed by numerous electron micro­ scopical and tracer investigations that supported earlier data on the in­ ternalization pathway of extraovarian proteins in follicles and on the role of coated vesicles in yolk deposition in insect oocytes (reviewed in 1 33) .

Regulation of the Amount of Starch in Plant Tissues by ADP Glucose Pyrophosphorylase

Abstract: Starch, a major storage metabolite in plants, positively affects the agricultural yield of a number of crops. Its biosynthetic reactions use adenosine diphosphate glucose (ADPGlc) as a substrate; ADPGlc pyrophosphorylase, the enzyme involved in ADPGlc formation, is regulated by allosteric effectors. Evidence that this plastidial enzyme catalyzes a rate-limiting reaction in starch biosynthesis was derived by expression in plants of a gene that encodes a regulatory variant of this enzyme. Allosteric regulation was demonstrated to be the major physiological mechanism that controls starch biosynthesis. Thus, plant and bacterial systems for starch and glycogen biosynthesis are similar and distinct from yeast and mammalian systems, wherein glycogen synthase has been demonstrated to be the rate-limiting regulatory step.

Notes on Pragmatism and Scientific Realism

Abstract: Research" (1991) is informative for the overview it provides of scientific realism. At the outset House tells the reader that he will forgo comparisons between scientific realism and interpretivism, pragmatism, and critical theory in order to focus on "its [scientific realism's] introduction and explication" (p. 2). At the end he poses the question: "How does scientific realism compare with perspectives such as interpretivism, pragmatism, and critical theory?" (p. 9). A note of response is not the place to pursue such comparisons in detail, but a few comments, perhaps, may provide the basis for beginning such comparisons, in this case between pragmatism and scientific realism. Pragmatism and scientific realism share a number of assumptions about science, language, and the world. Both are also opposed to positivism/empiricism. Given their areas of agreement as well as some common opponents, it is surprising that these two schools of thought end up so far apart. The following comments profile a few of their affinities as well as a few dramatic differences that divide them.

Prostanoid biosynthesis and mechanisms of action

Abstract: Prostanoids are local hormones formed from arachidonic acid that coordinate responses to circulating hormones which elicit prostanoid synthesis. For example, in the kidney, prostaglandin (PG) E2 synthesized by collecting tubule epithelia in response to arginine vasopressin (AVP) acts on the parent collecting tubule as well as the neighboring thick limb to modulate NaCl and water reabsorption occurring in response to AVP. Studies performed over the last 15 years have defined the major cellular and subcellular sites of PG synthesis in the kidney. In addition, it is now recognized that the multiple cellular actions of prostanoids in the kidney are mediated through receptors coupled to guanine nucleotide regulatory proteins. The goal of this review is to summarize recent biochemical and molecular biological studies on prostanoid biosynthetic enzymes and on prostanoid receptors. The major topics to be addressed are 1) phospholipid precursors of arachidonate, 2) membrane-associated and cytosolic phospholipase A2s, 3) PG endoperoxide (PGH) synthase isozymes, 4) thromboxane A (TxA) synthase, and 5) TxA/PGH and PGE receptors.

Modeling soil organic matter in organic-amended and nitrogen-fertilized long-term plots

Abstract: To study the effects of organic matter and fertilizer additions on soil organic-matter (SOM) dynamics, we analyzed results from a 30yr-old Swedish field experiment, using the CENTURY model. Field treatments on a sandy clay loam included biannual addition (up to 4000 kg C ha ) of straw, sawdust, and no organic additions, with and without N fertilizer (80 kg N ha), and green manure, farmyard manure, and bare fallow. Soil C and N, crop production (small-grain and root crops), N uptake, and mineralization and immobilization of N were modeled and compared with field measurements. Changes in soil C and N, as much as 30% after 30 yr, were generally well represented by the model. Most of the treatment differences in SOM could be explained by the rate of organic-matter input, its lignin content, and C/N ratio, plus the effect of N fertilizer on belowground C inputs. However, there appeared to be additional positive effects of N supply on SOM accumulation that were not fully explained by the model. The quality of organic amendments strongly influenced N uptake and crop productivity, through controls on N mineralization and immobilization. Mean annual N uptake ranged from a low of 3.1 g m 2 in sawdust-amended soil to a high of 9.2 g m 2 in fertilized, strawamended soil. Simulated N losses accounted for 7 to 20% of total N inputs. Nitrogen-balance estimates by the model were consistent with the observed data for four of the treatments, but treatments with low N availability appeared to have additional, unexplained N inputs. View complete article To view this complete article, insert Disc 5 then click button8

Map-based cloning of a gene controlling omega-3 fatty acid desaturation in Arabidopsis

Abstract: A gene from the flowering plant Arabidopsis thaliana that encodes an omega-3 desaturase was cloned on the basis of the genetic map position of a mutation affecting membrane and storage lipid fatty acid composition. Yeast artificial chromosomes covering the genetic locus were identified and used to probe a seed complementary DNA library. A complementary DNA clone for the desaturase was identified and introduced into roots of both wild-type and mutant plants by Ti plasmid-mediated transformation. Transgenic tissues of both mutant and wild-type plants had significantly increased amounts of the fatty acid produced by this desaturase.

A disagreement about within-group agreement: Disentangling issues of consistency versus consensus.

Abstract: James, Demaree, and Wolf (1984) developed an indes, r WG , for assessing within-group agreement appropriate when only a single target is rated. The assessment of interperceiver agreement in such situations is of particular relevance to the composition model for climate. Schmidt and Hunter (1989) have criticized the conceptual foundation of r WG because it is not consistent with the classical model of reliability. They proposed an alternative approach, the use of the rating standard deviation (SD X ), the standard error of the rating mean (SE M ), and the associated confidence intervals for SE M to index interrater agreement. This comment argues that the critique of r WG dit not clearly distinguish the concepts of interrater consensus (i.e., agreement) and interrater consistency (i.e., reliability)

Solutions to shape and topology eigenvalue optimization problems using a homogenization method

Abstract: A solution strategy to find the shape and topology of structures that maximize a natural frequency is presented. The methodology is based on a homogenization method and the representation of the shape of the structure as a material property. The problem is formulated as a reinforcement problem in which a given structure is reinforced using a prescribed amount of material. Two dimensional, plane elasticity problems are considered. Examples are presented for illustration.

Behavioral foundations of community emergency planning

Abstract: An overview of emergency management community emergency planning functional analysis of organizational response to emergencies organizational actions in protective action selection and population warning models of warning responses processes disaster images and their origins - pre-impact factors affecting warning response warning reception and response protective action selection and implementation involving the community in emergency preparedness and response.

An Arabidopsis mutant defective in the general phenylpropanoid pathway.

Abstract: Mutants of Arabidopsis deficient in a major leaf phenylpropanoid ester, 2-O-sinapoyl-L-malate, were identified by thin-layer chromatographic screening of methanolic leaf extracts from several thousand mutagenized plants. Mutations at a locus designated SIN1 also eliminate accumulation of the sinapic acid esters characteristic of seed tissues. Because of increased transparency to UV light, the sin1 mutants exhibit a characteristic red fluorescence under UV light, whereas wild-type plants have a blue-green appearance due to the fluorescence of sinapoyl malate in the upper epidermis. As determined by in vivo radiotracer feeding experiments, precursor supplementation studies, and enzymatic assays, the defect in the sin1 mutants appears to block the conversion of ferulate to 5-hydroxyferulate in the general phenylpropanoid pathway. As a result, the lignin of the mutant lacks the sinapic acid-derived components typical of wild-type lignin.

Contextual Effects on the Self-Perceived Efficacy of High School Teachers.

Abstract: If the self-efficacy of high school teachers is situated rather than global, it ought to vary within teachers (across a teacher's several assigned classes), as well as among teachers. An analysis of survey data from academic teachers in 16 high schools confirmed the existence of substantial intrateacher variation and revealed that a teacher tends to feel most efficacious when teaching high-track students. This effect is most pronounced for math and science teachers and disappears when the level of student engagement is controlled. A teacher's level of preparation and the grade level of the class also predict intrateacher variation. An analysis of interteacher variation revealed that teachers who exercise control over key working conditions and work in highly collaborative environments have elevated self-efficacy.

Polyhydroxybutyrate, a Biodegradable Thermoplastic, Produced in Transgenic Plants

Abstract: Polyhydroxybutyrate (PHB), a high molecular weight polyester, is accumulated as a storage carbon in many species of bacteria and is a biodegradable thermoplastic. To produce PHB by genetic engineering in plants, genes from the bacterium Alcaligenes eutrophus that encoded the two enzymes required to convert acetoacetyl-coenzyme A to PHB were placed under transcriptional control of the cauliflower mosaic virus 35S promoter and introduced into Arabidopsis thaliana. Transgenic plant lines that contained both genes accumulated PHB as electron-lucent granules in the cytoplasm, nucleus, and vacuole; the size and appearance of these granules were similar to the PHB granules that accumulate in bacteria.

Managing Insect Resistance to Bacillus thuringiensis Toxins

Abstract: Bacillus thuringiensis (B.t.) δ-endotoxins provide an alternative to chemical insecticides for controlling many species of pest insects. Recent biotechnological developments offer the promise of even greater use of B.t. toxins in genetically transformed pest-resistant crops. However, the discovery that insects can adapt to these toxins raises concerns about the long-term usefulness of B.t. toxins. Several methods for managing the development of resistance to B.t. toxins have been suggested, but none of these approaches offer clear advantages in all situations.

A quick and inexpensive method for removing polysaccharides from plant genomic DNA.

Abstract: A quick and inexpensive method has been demonstrated to remove polysaccharide contamination from plant DNA. Isolated plant genomic DNA with polysaccharide contaminants was dissolved in TE (10 mM Tris-HCl, pH 7.4, 1 mM EDTA) with NaCl ranging from 0.5-3.0 M, then precipitated with two volumes of ethanol. Most of the polysaccharides were removed effectively in a single high-salt precipitation at 1.0-2.5 M NaCl. At 3.0 M NaCl, the salt precipitated out of solution. Purified DNA was easily digested by either HindIII or EcoRI and was satisfactory as a template for PCR. The results show that high-salt precipitation effectively removed polysaccharides and their inhibitory effects on restriction enzyme and Taq polymerase activity.