Showing papers by "University of Colorado Boulder published in 1976"
TL;DR: The meta-analysis of research as discussed by the authors is an important feature of the research and evaluation enterprise, and it has been widely used in the field of computer science and computer engineering, especially in the context of education.
Abstract: M y subject is data analysis at three levels. Primary analysis is the original analysis of data in a research study. It is what one typically imagines as the application of statistical methods. Secondary analysis is the re-analysis of data for the purpose of answering the original research question with better statistical techniques, or answering new questions with old data. Secondary analysis is an important feature of the research and evaluation enterprise. Tom Cook (1974) at Northwestern University has written about its purposes and methods. Some of our best methodologists have pursued secondary analyses in such grand style that its importance has eclipsed that of the primary analysis. We can cite with pride some state of the art documents: the MostellerMoynihan secondary analysis of the Coleman study; the Campbell-Erlebacher analysis of the Ohio-Westinghouse Headstart evaluation; and the Elashoff-Snow secondary analysis of Pygmalion in the Classroom, to name three. About all that can effectively be done to insure that secondary analyses of important studies are carried out is to see that the data from the original studies are preserved and that secondary analyses are funded. The preservation of original data could improve. Last month, one of our graduate students, Karl White, spent 15 hours and made 30 phone calls attempting to obtain from the government a copy of the data tapes for the Coleman study only to learn in the end that they had been irretrievably filed in unmarked tape cannisters with some 2,000 other unmarked data tapes. Tom Cook remarked in an Annual Meeting symposium on secondary analysis that you can get the data if you have chutzpah or if you're socio metrically well-connected. The whole business is too important to be treated so casually. On the other extreme, one can point with satisfaction to the ready availability to any researcher of the data tapes from Project TALENT or the National Assessment of Educational Progress. Others are advancing the practice of secondary analysis. My major interest currently is in what we have come to call—not for want of a less pretentious name—the meta-analysis of research. The term is a bit grand, but it is precise, and apt, and in the spirit of "metamathematics," "meta-psychology," and "meta-evaluation." Meta-analysis refers to the analysis of analyses. I use it to refer to the statistical analysis of a large collection of analysis results from individual studies for the purpose of integrating the findings. It connotes a rigorous alternative to the casual, narrative discussions of research studies which typify our attempts to make sense of the rapidly expanding research literature. The need for the meta-analysis of research is clear. The literature on dozens of topics in education is growing at an astounding rate. In five years time, researchers can produce literally hundreds of studies on IQ and creativity, or impulsive vs. reflective cognitive styles, or any other topic.
4,509 citations
TL;DR: In this paper, a multiple regression computer program was utilized to derive an equation for prediction of the physician's over-all ratings from a subset of the predictor variables fulfilling a combination of constraints.
3,262 citations
TL;DR: In this paper, an external specification of a digital filter is investigated via the internal structure of the filter using a state variable formulation, and conditions for minimizing this output noise are established and realizations which meet these conditions are constructed.
Abstract: Beginning with an external specification of a digital filter, structures which minimize roundoff noise are investigated. After fixing the probability of overflow through an l_{2} scaling procedure, roundoff noise is studied via the internal structure of the filter using a state variable formulation. An output noise variance formula in terms of the internal structure is derived. Conditions for minimizing this output noise are established and realizations which meet these conditions are constructed. A new set of filter invariants called second-order modes are defined and shown to play a definitive role in minimal noise realizations. From these invariants, for example, one can calculate the minimal output noise variance of a given external specification. Numerical results are given which compare these new filter structures with the usual parallel and cascade connections of second-order filters, both theoretically and through simulations. For narrow-band filters, these new structures can be orders of magnitude better (in terms of output noise variance). One drawback of these new structures is a large increase in the number of multipliers needed to realize them. However, by applying the theory to subfilters connected in parallel and cascade, a good compromise between output noise and number of multipliers is obtained.
774 citations
TL;DR: A morphological study of the growth and the development of the reproductive system of the nematode Caenorhabditis elegans has been carried out and it is shown that the mature gonad presents a linear developmental axis both temporally and morphologically of the formation of oocytes, fertilization, and the early stages of embryogenesis.
567 citations
TL;DR: The R-matrix concept of atomic processes was first introduced by Wigner and Eisenbud as mentioned in this paper with the fundamental idea that configuration space describes the scattered particle, and the target is divided into two regions.
Abstract: Publisher Summary This chapter discusses the R-matrix concept of atomic processes. The R-matrix method was first introduced by Wigner and Eisenbud with a fundamental idea that configuration space describes the scattered particle, and the target is divided into two regions. In the internal region (r
498 citations
TL;DR: The presence of a dsRNA-dependent protein kinase activity in interferon cell sap is reported, which does not correspond either to the major polypeptide product of theinterferon-dsRNA specific phosphorylation, or, presumably, to phosphorylated IF-E2.
Abstract: PROTEIN synthesis in cell-free systems from mouse L-cells pretreated with the antiviral agent interferon1 shows an enhanced sensitivity to inhibition by double-stranded RNA (dsRNA)2,3. The possible significance of this with respect to events in intact interferon-treated virus-infected cells has already been discussed2,4. We have already shown that the addition of small amounts of a post-ribosomal supernatant fraction from interferon-treated cells (interferon cell sap) renders protein synthesis in control cell-free systems sensitive to inhibition by dsRNA4. Our results are in accord with a two-step model involving an initial 100-fold activation of an inhibitor on incubation of the interferon cell sap with ATP and dsRNA (activation step), the activated inhibitor then interacting with the protein-synthetic system to inhibit translation (inhibitory step)5. In view of the dependence of the inhibition of protein synthesis upon incubation with ATP as well as dsRNA5 it was of interest to determine if a protein kinase(s) is involved, as seems to be the case in reticulocyte lysates in which phosphorylation of the initiator Met-tRNA binding factor (IF-E2) has been implicated following incubation of the lysates under a variety of inhibitory conditions including the presence of dsRNA (P. Farrell, K. Balkow, T. Hunt and R. J. Jackson, personal communication)6. In accord with this, we report here the presence of a dsRNA-dependent protein kinase activity in interferon cell sap. The inhibitor of protein synthesis which is activated on incubation of interferon cell sap with ATP and dsRNA, however, is heat stable and of relatively low molecular weight. It does not correspond either to the major polypeptide product of the interferon-dsRNA specific phosphorylation, or, presumably, to phosphorylated IF-E2.
409 citations
TL;DR: Larval forms of the free-living soil nema-tode, Caenorhabditis elegans, possess the ability to enter a semi-dormant, quiescent state referred to as the dauer larval stage (German, “enduring” larva), which enables the species to retard its ageing rate and extend its life span.
Abstract: THE study of mechanisms affecting the rate of ageing can be facilitated by naturally occurring phenomena, innate to some organisms, that enable the species to retard its ageing rate and extend its life span1. Such a phenomenon exists in certain species of nematode. Larval forms of the free-living soil nema-tode, Caenorhabditis elegans, possess the ability to enter a semi-dormant, quiescent state referred to as the dauer larval stage (German, “enduring” larva). Newly hatched larvae of C. elegans undergo four larval stages (L1–L4) punctuated by moulting. If larvae are starved, they will enter the dauer state during the second larval moult. At this time, the old cuticle is replaced by a special, relatively impermeable cuticle unique to dauer larvae2.
388 citations
TL;DR: In this paper, an elicitor of phytoalexin production in soybean (Glycine max L.) tissues was isolated from purified Phytophthora megasperma var. sojae mycelial walls by a heat treatment similar to that used to solubilize the surface antigens from the cell walls of Saccharomyces cerevisiae.
Abstract: An elicitor of phytoalexin production in soybean (Glycine max L.) tissues was isolated from purified Phytophthora megasperma var. sojae mycelial walls by a heat treatment similar to that used to solubilize the surface antigens from the cell walls of Saccharomyces cerevisiae. The wall-released elicitor is a discrete, minor portion of the P. megasperma var. sojae mycelial walls. The elicitor released from the mycelial walls was divided by diethylaminoethylcellulose and concanavalin A-Sepharose chromatography into four fractions, each having different chemical characteristics. The four fractions were obtained from each of the three races of P. megasperma var. sojae. The corresponding fractions from each of the three races are very similar in composition and elicitor activity. The results suggest that the elicitor activity of each fraction resides in the glucan component of the fraction. Evidence is presented to demonstrate that the elicitors are not race-specific and that the accumulation of glyceollin is not sufficient to account for race-specific resistance.
370 citations
TL;DR: In this paper, the authors present an efficient implementation of Edmonds' algorithm for finding a maximum matching, which is based on a system of labels that encodes the structure of alternating paths.
Abstract: A matching on a graph is a set of edges, no two of which share a vertex. A maximum matching contains the greatest number of edges possible. This paper presents an efficient implementation of Edmonds' algorithm for finding a maximum matching. The computation time is proportional to V3, where V is the number of vertices; previous implementations of Edmonds' algorithm have computation time proportional to V4. The implementation is based on a system of labels that encodes the structure of alternating paths.
317 citations
TL;DR: Sodium butyrate appears to have properties of a good chemotherapeutic agent for neuroblastoma tumors because the treatment of Neuroblastoma cells in culture causes cell death and “differentiation”; however, it is either innocuous or produces reversible morphological and biochemical alterations in other cell types.
Abstract: Sodium butyrate produces reversible changes in morphology, growth rate, and enzyme activities of several mammalian cell types in culture. Some of these changes are similar to those produced by agents which increase the intracellular level of adenosine 3′,5′-cyclic monophosphate (cAMP) or by analogs of cAMP. Sodium butyrate increases the intracellular level of cAMP by about two fold in neuroblastoma cells; therefore, some of the effects of sodium butyrate on these cells may in part be mediated by cAMP. Sodium butyrate appears to have properties of a good chemotherapeutic agent for neuroblastoma tumors because the treatment of neuroblastoma cells in culture causes cell death and “differentiation”; however, it is either innocuous or produces reversible morphological and biochemical alterations in other cell types.
314 citations
TL;DR: The presumptive benefits of electronic fetal monitoring for improving fetal outcome were not found and there were no differences in the infant outcomes in any measured category between the electronically monitored group and the auscultated group.
TL;DR: The ways that the methods of data flow analysis can be applied to improve software reliability are described and how fast algorithms can be used to implement a classification scheme for data flow are shown.
Abstract: The ways that the methods of data flow analysis can be applied to improve software reliability are described. There is also a review of the basic terminology from graph theory and from data flow analysis in global program optimization. The notation of regular expressions is used to describe actions on data for sets of paths. These expressions provide the basis of a classification scheme for data flow which represents patterns of data flow along paths within subprograms and along paths which cross subprogram boundaries. Fast algorithms, originally introduced for global optimization, are described and it is shown how they can be used to implement the classification scheme. It is then shown how these same algorithms can also be used to detect the presence of data flow anomalies which are symptomatic of programming errors. Finally, some characteristics of and experience with DAVE, a data flow analysis system embodying some of these ideas, are described.
TL;DR: Routine intrapartum pharyngeal suctioning with a DeLee catheter of infants with meconium staining has significantly reduced the incidence and severity ofmeconium aspiration syndrome (MAS).
TL;DR: Two bioassays were developed and characterized and the extracellular Pms elicitor was determined to be a predominantly 3-linked glucan, which is similar in composition and structure to a polysaccharide component of Pms mycelial walls.
Abstract: Resistance of soybean (Glycine max L.) seedlings to Phytophthora megasperma var. sojae (Pms) is in part due to the accumulation in infected tissue of a compound which is toxic to Pms. The accumulation of this compound, a phytoalexin called glyceollin, is triggered by infection, but it can also be triggered by molecules, "elicitors," present in cultures of Pms. The ability of the Pms elicitor to stimulate phytoalexin accumulation in soybean tissues has been used as the basis for biological assays of elicitor activity. Two bioassays were developed and characterized in this study of the Pms elicitor. These bioassays use the cotyledons and the hypocotyls of soybean seedlings. The cotyledon assay was used to characterize the extracellular Pms elicitor. This elicitor was isolated from Pms cultures and purified by ion exchange and molecular sieving chromatography. The extracellular Pms elicitor was determined to be a predominantly 3-linked glucan, which is similar in composition and structure to a polysaccharide component of Pms mycelial walls.
TL;DR: The human diploid cell line, WI-38, has proven to be an especially good object for high-voltage electron microscopy using whole cells, and the approach combined with stereo-microscopy has extended the knowledge of cellular ultrastructure.
Abstract: The human diploid cell line, WI-38, has proven to be an especially good object for high-voltage electron microscopy using whole cells. Cells of intermediate passages were grown on plastic-coated, carbon-shadowed gold grids, fixed with glutaraldehyde, post-fixed with osmium tetroxide, stained with uranyl salts and critical-point dried. The absence of an embedding matrix produces images of increased contrast and resolution.
The approach combined with stereo-microscopy has extended our knowledge of cellular ultrastructure. Stereo-images of whole cells reveal nuclei, mitochondria, microtubules, microfilaments, the endoplasmic reticulum and ribosomes in their expected forms. At high magnifications a continuity of microtubules, microfilaments and membranous elements with thin (3–6 nm) strands of the ground substance has been observed. These strands form a three-dimensional lattice or mesh that pervades all parts of the cytoplasm. The entire structure is referred to as a microtrabecular lattice or mesh, the strands being the trabeculae. The inclusion of microtubules, microfilaments, ribosomes and vesicles of the endoplasmic reticulum within the material of the lattice makes them all part of a totally organized cytoplast.
TL;DR: The results suggest that changes in the density of adrenergic receptors are involved in 6-hydroxydopamine-induced supersensitivity at central noradrenergic synapses.
Abstract: The intraventricular administration of 6-hydroxydopamine, a procedure which destroys noradrenergic nerve terminals in the central nervous system, caused an increase in the density of beta-adrenergic receptors in rat cerebral cortex, without affecting their affinity for isoproterenol. The results suggest that changes in the density of adrenergic receptors are involved in 6-hydroxydopamine-induced supersensitivity at central noradrenergic synapses.
TL;DR: These studies explain the development of the previously mysterious Eck fistula syndrome, provide clues about in-vivo cell growth control by hormones, and suggests new lines of inquiry about the pathogenesis and/or treatment of several human disease processes.
TL;DR: An efficient algorithm for obtaining solutions is given and shown to be closely related to a well-known algorithm of Levinson and the Jury stability test, which suggests that they are fundamental in the numerical analysis of stable discrete-time linear systems.
Abstract: It is common practice to partially characterize a filter with a finite portion of its impulse response, with the objective of generating a recursive approximation. This paper discusses the use of mixed first and second information, in the form of a finite portion of the impulse response and autocorrelation sequences. The discussion encompasses a number of techniques and algorithms for this purpose. Two approximation problems are studied: an interpolation problem and a least squares problem. These are shown to be closely related. The linear systems which form the solutions to these problems are shown to be stable. An efficient algorithm for obtaining solutions is given and shown to be closely related to a well-known algorithm of Levinson and the Jury stability test. The close connection between these algorithms suggests that they are fundamental in the numerical analysis of stable discrete-time linear systems.
TL;DR: In this article, the authors measured the seafloor slope of modern and ancient wave-cut platforms on Ben Lomond Mountain in central California and found that they have a seaward slope composed of two segments: a steeper, slightly concave inshore segment, with gradients of generally 0.02 to 0.04 (20 to 40 m/km), and a flatter, planar offshore segment with gradient of 0.017 (7 to 17m/km).
Abstract: Modern and ancient wave-cut platforms on Ben Lomond Mountain in central California are broadly similar in shape. They have a seaward slope composed of two segments: a steeper, slightly concave inshore segment, with gradients of generally 0.02 to 0.04 (20 to 40 m/km), and a flatter, planar offshore segment with gradients of 0.007 to 0.017 (7 to 17 m/km). The flattest inshore and offshore gradients measured were, respectively, 0.015 (15 m/km) and 0.005 (5 m/km), suggesting that these are close to minimum gradients for erosional platforms in central California. The inshore segments are generally 300 to 600 m wide and extend to a depth of 8 to 13 m. Platforms are widest in areas where soft sandstone crops out and where there has been least uplift. Major storm waves now break in water 7 to 12 m deep. We conclude that inshore platform segments were associated with storm-wave surf zones and that offshore segments were associated with the zone of deep-water wave transformation. A gradient of 0.005 for the offshore segment would keep wave energy at the bottom constant (Zenkovich, 1967). A steeper gradient for the inshore segment would enable backwash undertow to counteract the strong onshore movement of surf, so that available coarse sediment could be moved laterally. Slopes less than the minimum would so dissipate wave energy in offshore areas that the surf zone would not be able to provide the needed longshore transport for coarse sediment, and beach progradation would result. Thus, platforms have a shape that allows efficient conversion of wave energy into erosion and longshore transport; their seaward gradient is not used for the downhill transport of sediment. Platform gradients decrease with time, at least until the minimum is achieved. Whether the offshore segments were eroded at their existing depths or were eroded by surf zones as sea level rose remains a matter of controversy. Ben Lomond platforms have been uplifted and progressively tilted in a seaward direction, indicating that late Tertiary domical uplift has continued into Quaternary time. Uplift rates have ranged from 0.16 m/1,000 yr near Santa Cruz to 0.26 m/1,000 yr near Greyhound Rock. Tilts have varied from 0.001 (1 m/km) for the lowest prominent platform to 0.009 (9 m/km) for the highest platform (which may be as old as 10 6 yr). Because of uplift, platforms must have been cut at times of eustatically high sea level.
TL;DR: Experience with two neonates with disorders circulatory adjustment at birth following prenatal exposure to indomethacin indicates that indometHacin may interfere with these adjustments in man and favor the development of the serious oxygen dependency known as primary pulmonary hypertension of the newborn.
TL;DR: The findings provide evidence that the site of SC synthesis in intestinal epithelium is secretory columnar cells, principally those in gland crypts and the polymeric immunoglobulins IgM and IgA are translocated through such SC-containing cells by a process that involves formation of cytoplasmic vesicles.
TL;DR: Computation of surface/volume ratios for biomass units of 27 coexisting phytoplankton species in a tropical lake indicates that these ratios are conserved within a range much narrower than expected by random choice of shapes.
Abstract: Plankton autotrophs vary greatly in size and shape. Computation of surface/volume ratios for biomass units of 27 coexisting phytoplankton species in a tropical lake indicates that these ratios are conserved within a range much narrower than expected by random choice of shapes. Conservation of surface/volume ratios suggests new explanations for the shapes of phytoplankton biomass units.
TL;DR: Although no single feature is pathognomonic, this constellation of epidemiologic and clinical findings, coupled with negative bacterial cultures, should suggest the possibility of neonatal enterovirus infection.
TL;DR: The family of filters generated from a prototype filter H(z) is shown to possess certain common properties which are coordinate-free quantities which are invariant under frequency transformation, which is significant in the design of low-noise fixed-point digital filter structures.
Abstract: The family of filters {H(F(z)):F(z) a frequency transformation} generated from a prototype filter H(z) is shown to possess certain common properties. These are coordinate-free quantities (called second-order modes) which are invariant under frequency transformation. The invariance is significant in the design of low-noise fixed-point digital filter structures since the second-order modes characterize the minimum attainable noise. Filter structures (including parallel, cascade, and ladder configurations) are studied whose output noise is essentially independent of bandwidth and center frequency. An analysis of direct form structures (whether isolated or as one section within a cascade or parallel configuration) results in an expression giving the dominant term in the output noise as a function of the parameter in the low-pass-low-pass transformation. This noise term approaches infinity as bandwidth approaches zero. Thus, for narrowband filters, a difference of several orders of magnitude in the output noise can exist between a scaled direct form (having six multiplications per two-pole section) and the optimal form (having nine multiplications per two-pole section).
TL;DR: DAVE, a system for analysing Fortran programs, is capable of detecting the symptoms of a wide variety of errors In programs, as well as assuring the absence of these errors.
Abstract: This paper describes DAVE, a system for analysing Fortran programs. DAVE is capable of detecting the symptoms of a wide variety of errors In programs, as well as assuring the absence of these errors. In addition, DAVE exposes and documents subtle data relations and flows within programs. The central analytic procedure used is a depth first search. DAVE itself is written in Fortran. Its implementation at the University of Colorado and some early experience are described.
TL;DR: In this article, the complexity of algorithms for two problems that arise in automatic test path generation for programs is analyzed, and it is shown that the problem of finding a path through a specified set of program statements is NP-complete.
Abstract: In this paper we analyze the complexity of algorithms for two problems that arise in automatic test path generation for programs: the problem of building a path through a specified set of program statements and the problem of building a path which satisfies impossible-pairs restrictions on statement pairs These problems are both reduced to graph traversal problems We give an efficient algorithm for the first, and show that the second is NP-complete
TL;DR: The temperature responses of the gonadogenic and zygote-defective mutants indicate a common association between functions in gonadogenesis and early embryogenesis, which implies that many of the functions required for development are general metabolic reactions under increased demand during differentiation and embryogenesis.
TL;DR: The structural data presented here, in concert with the biological data presented in the previous two papers, demonstrate that the only compound produced by P. megasperma var.
Abstract: The structures of the four wall-released elicitor fractions isolated from the Phytophthora megasperma var. sojae mycelial walls have been examined. The results demonstrate that fraction I is primarily composed of a branched beta-1,3-glucan, similar in structure to the extracellular elicitors described previously (Ayers, A., J. Ebel, F. Finelli, N. Burger, and P. Albersheim. 1976. Plant Physiol. 57: 751-759). Fractions II and IV are primarily composed of a highly branched mannan-containing glycoprotein, with fraction IV richer in protein than fraction II. Fraction III contains, attached to protein, a mixture of the two polysaccharide types found in fraction I and in fractions II and IV. The structural data presented here, in concert with the biological data presented in the previous two papers (Ayers et al. 1976. Plant Physiol. 57: 751-759; 760-765), demonstrate that the only compound produced by P. megasperma var. sojae which contains elicitor activity is the glucan. Evidence is presented that the terminal glycosyl residues of the glucan are required for elicitor activity. In addition, it is demonstrated that 90% of the glucan can be removed enzymically without any loss of biological activity. The active residue of the enzymic digestion is a highly branched 3- and 3,6-linked glucan containing about 4% mannosyl residues. The results presented suggest that the mannosyl residues of the glucan, which represent only about 1% of the undegraded glucan, are likely to participate in the active site of this molecule. The role of elicitors and phytoalexins in host-pathogen interactions is discussed. Evidence for the existence of and possible identity of another factor, which determines race specificity of host-pathogen interactions, is summarized.