Showing papers by "Michigan State University published in 1989"

The Message in Daily Exchange Rates: A Conditional-Variance Tale

Abstract: Formal testing procedures confirm the presence of a unit root in the autoregressive polynomial of the univariate time series representation of daily exchange-rate data. The first differences of the logarithms of daily spot rates are approximately uncorrelated through time, and a generalized autoregressive conditional heteroscedasticity model with daily dummy variables and conditionally t-distributed errors is found to provide a good representation to the leptokurtosis and time-dependent conditional heteroscedasticity. The parameter estimates and characteristics of the models are found to be very similar for six different currencies. These apparent stylized facts carry over to weekly, fortnightly, and monthly data in which the degree of leptokurtosis and time-dependent heteroscedasticity is reduced as the length of the sampling interval increases.

The eicosanoids and their biochemical mechanisms of action.

Abstract: Low dosages of aspirin [1,2] and ingestion of certain fish oils [3-6] have recently been touted as having some value in preventing cardiovascular disease. Aspirin is a nonsteroidal anti-inflammatory drug which exerts its action by inhibiting the synthesis of prostaglandins. The abundant w)3 polyunsaturated fatty acids of fish oils derived from cod and salmon also affect the synthesis of prostaglandins, as well as the synthesis of the leukotrienes and related hydroxy fatty acids; the effects of 3 fatty acids on prostaglandin and leukotriene synthesis result from the ability of O3 fatty acids to replace the more

Genetic imprinting suggested by maternal heterodisomy in non-deletion Prader-Willi syndrome

Abstract: Prader-Willi syndrome (PWS) is the most common form of dysmorphic genetic obesity associated with mental retardation. About 60% of cases have a cytological deletion of chromosome 15q11q13 (refs 2, 3). These deletions occur de novo exclusively on the paternal chromosome. By contrast, Angelman syndrome (AS) is a very different clinical disorder and is also associated with deletions of region 15q11q13 (refs 6-8), indistinguishable from those in PWS except that they occur de novo on the maternal chromosome. The parental origin of the affected chromosomes 15 in these disorders could, therefore, be a contributory factor in determining their clinical phenotypes. We have now used cloned DNA markers specific for the 15q11q13 subregion to determine the parental origin of chromosome 15 in PWS individuals not having cytogenetic deletions; these individuals account for almost all of the remaining 40% of PWS cases. Probands in two families displayed maternal uniparental disomy for chromosome 15q11q13. This is the first demonstration that maternal heterodisomy--the presence of two different chromosome 15s derived from the mother--can be associated with a human genetic disease. The absence of a paternal contribution of genes in region 15q11q13, as found in PWS deletion cases, rather than a mutation in a specific gene(s) in this region may result in expression of the clinical phenotype. Thus, we conclude that a gene or genes in region 15q11q13 must be inherited from each parent for normal human development.

A comprehensive literature review and analysis of the design, balancing and scheduling of assembly systems

Abstract: SUMMARY This paper reports the results of a comprehensive review and analysis of the assembly line balancing literature. Quantitative developments and qualitative issues are addressed at both the strategic and tactical levels. The numerous quantitative and qualitative factors which the literature mentions could impact the design, balancing and scheduling of assembly systems are organized into an eight-level hierarchical, factor/decision taxomony. This comprehensive taxonomy is used to assess our progress in assembly system design and operation. Finally, from the results of the literature review and progress assessment, suggestions for future research on socio-technical assembly systems are offered.

Promoting Access to Knowledge, Strategy, and Disposition in Students: A Research Synthesis:

Abstract: The emphasis in this paper is on access, defined as the ability to draw on or utilize one’s intellectual resources in situations where those resources are relevant. A number of factors influence access. They have been identified in various strands of research representing different construct and curriculum perspectives. To date, few attempts have been made to synthesize this research. This is the purpose of the present paper, which utilizes a framework thought to have relevance across research domains. According to this framework, two factors influence students’ ability to access knowledge, strategy, and disposition. The first is organizational in nature, the second relates to the amount of reflective awareness possessed by the individual. This paper discusses how organization and awareness factors influence access in each of the informational categories and how teachers can better attend to these factors and thus promote access or transfer in students.

Random field models in image analysis

Abstract: Image models are useful in quantitatively specifying natural constraints and general assumptions about the physical world and the imaging process. This review paper explains how Gibbs and Markov random field models provide a unifying theme for many contemporary problems in image analysis. Random field models permit the introduction of spatial context into pixel labeling problems, such as segmentation and restoration. Random field models also describe textured images and lead to algorithms for generating textured images, classifying textures and segmenting textured images. In spite of some impressive model-based image restoration and texture segmentation results reported in the literature, a number of fundamental issues remain unexplored, such as the specification of MRF models, modeling noise processes, performance evaluation, parameter estimation, the phase transition phenomenon and the comparative analysis of alternative procedures. The literature of random field models is filled with great promise, but...

Job and life satisfaction: A reevaluation of the strength of the relationship and gender effects as a function of the date of the study.

Abstract: Etude meta-analytique de 34 recherches effectues dans differents secteurs des sciences humaines sur les rapports entre les satisfactions vis-a-vis de l'existence et du travail

Enzymes of Ethylene Biosynthesis

Abstract: The properties of enzymes involved in ethylene biosynthesis are reviewed and progress toward the purification of these enzymes is described. The enzyme whose activity usually limits ethylene biosynthesis is 1-aminocyclopropane-1-carboxylate (ACC) synthase. Even though its level in plants is extremely low, it has now been purified from several sources. The enzyme that converts ACC to ethylene does not survive homogenization, apparently because it is membrane-bound and because its activity requires membrane integrity. Properties of this enzyme have been elucidated in vivo and in vacuolar preparations which possess the capacity to convert ACC to ethylene.

Teachers' Pedagogical Content Beliefs in Mathematics

Abstract: This study examined relationships among first-grade teachers' pedagogical content beliefs, teachers' pedagogical content knowledge, and students' achievement in mathematics. Teachers (N = 39) completed structured questionnaires and interviews on their beliefs and knowledge about instruction, children's learning, and the mathematics content in addition and subtraction. Results indicated significant positive relationships among teachers' beliefs, teachers' knowledge, and students' problem-solving achievement. Compared to teachers with a less cognitively based perspective (LCB teachers), teachers with a more cognitively based perspective (CB teachers) made extensive use of word problems in introducing and teaching addition and subtraction. They also spent time developing children's counting strategies before teaching number facts. CB teachers had greater knowledge of word problem types and greater knowledge of their children's problem-solving strategies than did LCB teachers. Furthermore, CB teachers obtaine...

Beyond the State: Civil Society and Associational Life in Africa

Abstract: The current scholarly preoccupation with the state may obscure more than it reveals for students of politics in sub-Saharan Africa. The weakly formed state in Africa—beset by decline in economic production and political authority—is now retreating from overambitious attempts at social transformation. The time is therefore ripe for societal actors to play an enhanced role in political change. This article reviews the current literature on state-society relations in Africa with particular emphasis on the nature of African associational life and the extent to which it is taking on a politically organized form as an identifiable civil society. The author proposes a theoretical framework and research agenda that takes account of the capacity of either state or societal actors to exercise a range of options to engage or disengage.

Global diversification strategy and corporate profit performance

Abstract: Based on a sample of 62 multinationals, this paper examines the impact of global diversification strategy on corporate profit performance by integrating the product and the international market dimensions of diversification. The results suggest that the corporate profit performance impact of related and unrelated diversification varies contingent upon the extent of a firm's international market diversification. One important lesson of this work is that both business strategy researchers and managers should review corporate diversification as having distinct yet interactive strategic dimensions—product and international market—and they would do well to recognize both the different and the joint effect of these dimensions on corporate profit performance.

The Psychology of Shame: Theory and Treatment of Shame-Based Syndromes

Abstract: In this classic volume, Kaufman synthesizes object relations theory, interpersonal theory, and, in particular, Silvan Tompkins's affect theory, to provide a powerful and multidimensional view of shame. Using his own clinical experience, he illustrates the application of affect theory to general classes of shame-based syndromes including compulsive; schizoid, depressive, and paranoid; sexual dysfunction; splitting; and sociopathic. This second edition includes two new chapters in which Dr. Kaufman presents shame as a societal dynamic and shows its impact on culture. He examines the role of shame in shaping the evolving identity of racial, ethnic, and religious minorities, and expands his theory of governing scenes. This new edition will continue to be of keen interest to clinical psychiatrists as well as graduate students.

Conductive polymer bronzes. Intercalated polyaniline in V2O5 xerogels

Abstract: La polymerisation vedox de l'audine dans les xerogels le V 2 O 5 ,nH 2 O donne un composite moleculaire contenant la forme protome de la polyaniline; la conductivite electrique et le coefficient le Seebecti du composite diminuent avec la temperature

Generalized Optimal Hedge Ratio Estimation

Abstract: A generalized approach to estimating optimal hedge ratios on futures markets is developed. The generalized approach is not difficult to apply and provides a framework for evaluating the appropriateness of conventional simple regression approaches to optimal hedge ratio estimation. In an application to storage hedging of corn, soybeans, and wheat, it is found that simple regression using price levels or returns leads to errors in optimal hedge ratio estimation but that simple regression using price changes provides reasonably accurate estimates.

Perspectives on measurement of denitrification in the field including recommended protocols for acetylene based methods

Abstract: Of the biogeochemical processes, denitrification has perhaps been the most difficult to study in the field because of the inability to measure the product of the process. The last decade of research, however, has provided both acetylene and 15N based methods as well as undisturbed soil core and in situ soil cover sampling approaches to implementing these methods. All of these methods, if used appropriately, give comparable results. Thus, we now have several methods, each with advantages for particular sites or objectives, that accurately measure denitrification in nature. Because of the general usefulness of the acetylene methods, updated protocols for the following three methods are given: gas-phase recirculation soil cores; static soil cores; and the denitrifying enzyme assay also known as the phase 1 assay. Despite the availability of these and other methods, denitrification budgets remain difficult to accurately establish in most environments because of the high spatial and temporal variability inherent in denitrification. Appropriate analysis of those data includes a distribution analysis of the data, and if highly skewed as is typically the case, the most accurate method to estimate the mean and the population variance is the UMVUE method (uniformly minimum variance unbiased estimator). Geostatistical methods have also been employed to improve spatial and temporal estimates of denitrification. These have occasionally been successful for spatial analysis but in the attempt described here for temporal analysis the approach was not useful.

Generalized measures of fault tolerance with application to N-cube networks

Abstract: In developing deterministic measures of system-level fault tolerance for multiple-processor systems, it has generally been assumed that any subset of system components (processors or links) can potentially fail at the same time. In the present work, the author generalizes these measures by restricting the potentially faulty sets to some subsets of the system components. Using this model, he presents a fault-tolerance analysis for the n-cube networks that shows that such networks can tolerate up to 2n-3 processor failures and remain connected provided that for each processor p in the network, all the processors which are directly connected to p do not fail at the same time. He also shows that in this situation the diameter of the network may increase only by a constant value. The author presents an O((kn)/sup 2/) time algorithm for determining if the network is disconnected when a set of k faulty processors, k >

Monoclonal Antibodies to the Alternative Oxidase of Higher Plant Mitochondria

Abstract: The higher plant mitochondrial electron transport chain contains, in addition to the cytochrome chain which terminates with cytochrome oxidase, an alternative pathway that terminates with an alternative oxidase. The alternative oxidase of Sauromatum guttatum Schott has recently been identified as a cluster of proteins with apparent Mr of 37, 36, and 35 kilodaltons (kD). Monoclonal antibodies have now been prepared to these proteins and designated as AOA (binding all three proteins of the alternative oxidase cluster), AOU (binding the upper or 37 kD protein), and AOL (binding the lower or 36 and 35 kD proteins). All three antibodies bind to their respective alternative oxidase proteins whether the proteins are in their native or denatured states (as on protein blots). AOA and AOU inhibit alternative oxidase activity around 49%, whereas AOL inhibits activity only 14%. When coupled individually to Sepharose 4B, all three monoclonal resins were capable of retaining the entire cluster of alternative oxidase proteins, suggesting that these proteins are physically associated in some manner. The monoclonals were capable of binding similar mitochondrial proteins in a number of thermogenic and nonthermogenic species, indicating that they will be useful in characterizing and purifying the alternative oxidase of different systems. The ability of the monoclonal-Sepharose 4B resins to retain the cluster of previously identified alternative oxidase proteins, along with the inhibition of alternative oxidase activity by these monoclonals, supports the role of these proteins in constituting the alternative oxidase.

Free Convection on a Vertical Stretching Surface

Abstract: On obtient des solutions en forme close pour la distribution de temperature pour tous les nombres de Prandtl multiples entiers de 1/2. On etudie la convection libre verticale. Une solution de similarite tridimensionnelle est presentee pour les equations entieres de Navier-Stokes-Boussinesq

Denitrification in north temperate forest soils: Spatial and temporal patterns at the landscape and seasonal scales

Abstract: Spatial and temporal patterns of denitrification were studied in nine forest soils of different texture and drainage classes in Michigan. Denitrification was measured using intact soil cores amended with acetylene. Sampling was done weekly during spring, and monthly at other times. To determine the factors limiting denitrification, selected cores were amended with either water or water plus nitrate. We found that activity was highest in spring and fall and was lowest during summer. Soils showed a characteristic relationship between denitrification rate and soil texture and drainage classes. Over 80% of the annual N loss to denitrification occurred during brief (3–6 week) periods of high activity in the spring and fall. Rates of denitrification during these periods exceeded 0.5kg N ha −1 d −1 in some soils. Estimates of annual N loss to denitrification ranged from −1 yr −1 in a well-drained sand soil to over 40kg N ha −1 yr −1 in a poorly-drained clay loam soil. Lack of available NO −1 1 was the primary factor limiting denitrification in summer, but available carbon was probably occasionally limiting, especially in the well-drained soils. Marked seasonal changes were observed in the variability and frequency distributions of denitrification rates. Denitrification rates showed lower variance in spring and fall compared to summer, regardless of the magnitude of the rates. These patterns may be related to seasonal changes in soil structure, carbon availability or aeration, which create a more uniform environment in the spring an fall. The characteristic relationship between denitrification rates and soil texture and drainage over two seasons and multiple sites suggests that geomorphologically-based models using these parameters may be feasible for producing landscape- and regional-scale estimates of denitrification.

Predation Risk and The Foraging Behavior of Competing Stream Insects

Abstract: Invertebrates that graze periphyton growing on stones in coldwater streams in Michigan are at greatest risk of predation from a benthic-feeding fish (the mottled sculpin, Cottus bairdi) while on the top surface of substrates, where periphyton is most abundant, and during the day, when sculpin feed most actively. We conducted laboratory experiments with larvae of two strong exploitative competitors for periphyton (the mayfly Baetis tri- caudatus and the caddisfly Glossosoma nigrior) to test if and how their foraging behavior was affected by presence of sculpin when sculpin were not allowed to attack prey. We incorporated four experimental factors in a factorial design: sculpin presence/absence, the abundance (low, high) of food that was patchily distributed on the top surface of substrates, grazer hunger level (fed, starved), and time of day (day, night). In feeding trials, Baetis was much more vulnerable than Glossosoma to sculpin pre- dation. Similarly, only the foraging behavior of Baetis was strongly affected by the presence of sculpin. Baetis larvae responded to the presence of sculpin by: (1) significantly reducing the time spent on the top surface of substrates, and their movement rate while moving within and between food patches, and (2) significantly increasing the proportion of time spent in food patches, and the proportion of individuals that left the substrate by drifting downstream. Baetis larvae accepted greater risk of predation (by spending more time on top) when food abundance on top was high and when larvae had been starved for 27 h. Also, Baetis behavior was strongly affected by sculpin presence during the day but not at night. Collectively, these results suggest that Baetis larvae made adaptive compromises between feeding and avoiding sculpin. In contrast, Glossosoma behavior was not affected by the presence of sculpin. Glossosoma responded most strongly to alterations in food density and their own hunger level. Our results suggest that the presence of sculpin, even though the fish consumed no larvae, might indirectly affect the outcome of competitive interactions between Baetis and Glossosoma through the grazers' differential behavioral responses to the predator.

Direct evidence that growth cones pull.

Abstract: THERE is controversy over whether axonal elongation is the result of a pulling growth cone and the role of tension in axonal elongationl-4. Earlier in this decade, the consensus was that axons or neurites elongated from tension generated by forward motility of the growth cone5,6. It was presumed that contractile filopodia were the source of the tension moving the growth cone7,8. But this view was challenged by experiments showing that neurites elongate, albeit abnormally, in the presence of cytochalasin, which inhibits growth-cone and filopodial movements9. Additionally, high resol-ution, video-enhanced observations of growth-cone activity argued against filopodial shortening as a source of tension, suggesting instead that an extrusion of cytoplasm rather than a pulling process, is the key event in neurite elongation1,3. Studies of slow axonal transport10, however, indicate that much slower cytoskeletal pushing underlies axonal elongation. We report here direct measurements of neurite force as a function of growth-cone advance which show that they are linearly related and accompanied by apparent neurite growth. No increase in force occurs in neurites whose growth cone fails to advance.