Showing papers by "Boston College published in 1988"

Institutional Ownership and Corporate R&D in the Computer Industry

Abstract: The article discusses a study on the relationship between institutional ownership and research and development (R&D) spending in several companies for the period 1980 to 1983, with a focus on the c...

Tutorial on high-level synthesis

Abstract: High-level synthesis takes an abstract behavioral specification of a digital system and finds a register-transfer level structure that realizes the given behavior. In this tutorial we will examine the high-level synthesis task, showing how it can be decomposed into a number of distinct but not independent subtasks. Then we will present the techniques that have been developed for solving those subtasks. Finally, we will note those areas related to high-level synthesis that are still open problems.

The Point of Words: Children's Understanding of Metaphor and Irony

Abstract: Metaphor and Irony in Communication Philosophical and Linguistic Approaches to Metaphor and Irony Measures of Metaphor Constraints on Metaphor Comprehension Early Metaphors in Spontaneous Speech Metaphor and Cognition How Children Misunderstand Irony Constraints on Irony Comprehension Why Children Understand Metaphor before Irony References Index

Psychological Effects of Unemployment on Workers and Their Families

Abstract: This paper reviews findings from a panel study of Boston area unemployed men and their families. Psychological effects of unemployment on workers and their wives are summarized, particularly for the first half year of joblessness. Family responses to job loss are also examined, including the role of the marital relationship in buffering workers' stress. Finally, policy and service implications of this research are discussed. Consideration is given not only to the mental health needs of workers, but to frequently overlooked qualities of efficacy and resilience among the unemployed.

Axon-sparing lesions of the preoptic region and substantia innominata disrupt maternal behavior in rats.

Abstract: In this study we investigated the effects of axon-sparing lesions of the preoptic region on the maternal behavior of postpartum rats. The lesions were produced with the excitotoxic amino acid N-methyl-D,L-aspartic acid (NMA). The first experiment determined that bilateral injections of NMA into the medial preoptic area (MPOA) of fully maternal lactating rats disrupted maternal behavior. In a second experiment, bilateral injections of NMA into the lateral preoptic area and adjoining substantia innominata (LP/SI region) also disrupted maternal behavior. A third experiment, employing horseradish peroxidase histochemistry, provided anatomical evidence that NMA destroys neuronal cell bodies while sparing fibers of passage. These findings were discussed with respect to the view that an MPOA-to-LP/SI-to-ventral tegmental area circuit underlies maternal behavior in the rat.

Escherichia coli aspartate transcarbamylase: the relation between structure and function

Abstract: The x-ray structures of the allosteric enzyme aspartate transcarbamylase from Escherichia coli have been solved and refined for both allosteric forms. The T form was determined in the presence of the heterotropic inhibitor cytidine triphosphate, CTP, while the R form was determined in the presence of the bisubstrate analog N-phosphonacetyl-L-aspartate. These two x-ray structures provide the starting point for an understanding of how allosteric enzymes are able to control the rates of metabolic pathways. Insights into the mechanisms of both catalysis and homotropic cooperativity have been obtained by using site-directed mutagenesis to probe residues thought to be critical to the function of the enzyme based on these x-ray structures.

The distortion of teaching and testing: High‐stakes testing and instruction

Abstract: (1988). The distortion of teaching and testing: High‐stakes testing and instruction. Peabody Journal of Education: Vol. 65, About Teachers and Teaching, pp. 29-46.

Categories versus groups as explanatory concepts in intergroup relations

Abstract: In this discussion of papers by Doise (1988) and Tajfel (1982) it is argued that a conceptual distinction should be made between social groups and social categories. A social group can be considered as a ‘dynamic whole’ or social system, characterized by the perceived interdependence among its members, whereas a social category can be defined as a collection of individuals who share at least one attribute in common. This distinction is crucial for the understanding of outgroup favouritism in the minimal intergroup situation, the basic similarity between large scale groupings and face-to-face groups, the difference between group identification and social identity and the issue of categorizations versus attributions in intergroup conflict.

A research program for establishing the validity of the price-quality relationship

Abstract: Despite over 30 years of empirical investigations, it remains unclear whether (1) there is an actual positive relationship between price and product quality, and (2) whether buyers perceive a positive relationship between price and product quality. Although there has been a plethora of studies on the relationship, there is little agreement on what we know about the relationship. The paper assesses the current state of knowledge on the relationship and argues for a better conceptual framework for understanding the price-quality relationship. Then the paper outlines a systematic research program for establishing the validity of the relationship, and establishes a set of criteria for evaluating the contribution to knowledge of future research on the price-quality relationship.

An Explication of the Philosophical Assumptions of the Roy Adaptation Model

Abstract: In this paper, the philosophical assumptions for theorizing and re search based on the Roy adaptation model of nursing are explicated. The common philosophical heritage of nursing and the author's perspec tive of the discipline are examined. Some highlights of the developments of the Roy adaptation model are reviewed. Eight assumptions about the adapting person in society are articulated, derived from the theorist's nursing heritage, perspective of the discipline, and specific life values. The philosophical assumptions are categorized by the general principles of humanism and veritivity, a term coined to connote the richness of rootedness in an absolute truth. This principle is compared to rational ism and relativism as two other world views. The author describes how veritivity as a world view leads to the values of conviction, commitment, and caring based on the value of the individual in society in the context of the purposefulness of all of human existence.

Function of arginine-166 in the active site of Escherichia coli alkaline phosphatase.

Abstract: The function of arginine residue 166 in the active site of Escherichia coli alkaline phosphatase was investigated by site-directed mutagenesis. Two mutant versions of alkaline phosphatase, with either serine or alanine in the place of arginine at position 166, were generated by using a specially constructed M13 phage carrying the wild-type phoA gene. The mutant enzymes with serine and alanine at position 166 have very similar kinetic properties. Under conditions of no external phosphate acceptor, the kcat for the mutant enzymes decreases by approximately 30-fold while the Km increases by less than 2-fold. When kinetic measurements are carried out in the presence of a phosphate acceptor, 1.0 M Tris, the kcat for the mutant enzymes is reduced by less than 3-fold, while the Km increases by more than 50-fold. For both mutant enzymes, in either the absence or the presence of a phosphate acceptor, the catalytic efficiency as measured by the kcat/Km ratio decreases by approximately 50-fold as compared to the wild type. Measurements of the Ki for inorganic phosphate show an increase of approximately 50-fold for both mutants. Phenylglyoxal, which inactivates the wild-type enzyme, does not inactivate the Arg-166----Ala enzyme. This result indicates that Arg-166 is the same arginine residue that when chemically modified causes loss of activity [Daemen, F.J.M., & Riordan, J.F. (1974) Biochemistry 13, 2865-2871]. The data reported here suggest that although Arg-166 is important for activity is not essential. The analysis of the kinetic data also suggests that the loss of arginine-166 at the active site of alkaline phosphatase has two different effects on the enzyme. First, the binding of the substrate, and phosphate as a competitive inhibitor, is reduced; second, the rate of hydrolysis of the covalent phosphoenzyme may be diminished.

Two- or three-stage least squares

Abstract: Two elements enter the choice between 2 and 3SLS for full-system estimation: statistical efficiency and computational cost. 2SLS always has the computational edge, but 3SLS can be more efficient, a relative advantage that increases with the strength of the interrelations among the error terms. A measure of these interrelations is thus helpful in making the choice, and, when there are only two equations, this has suggested using a high pairwise error correlation as an indicator of when to use 3SLS. In larger systems of equations, however, these pairwise correlations can remain small even though more general interrelations give 3SLS the relative advantage. More general indicators are therefore needed, and this paper suggests three such and demonstrates their efficacy.

Sex differences in English language acculturation and learning strategies among Vietnamese adults aged 40 and over in the United States

Abstract: This study examines sex differences in English language acculturation and learning strategies among older Vietnamese in the United States in a nationwide probability sample. Data of this study came from the Southeast Asian Refugee Self-Sufficient Study (1982). The results reveal that older Vietnamese women had more problems with their English language than older Vietnamese men. In addition, the Vietnamese men were more likely to use various learning strategies to improve their English skills than the women.

Substitutability of Leases and Debt in Corporate Capital Structures

Abstract: Finance theory suggests that leases and debt are substitutes. Surprisingly, however, prior empirical research using financial statement data has been unable to verify this trade-off between the two forms of financing. This study re-examines the issue of substitutability by comparing changes in lease and debt financing over a six-year horizon for a large sample of U.S. firms. The empirical results strongly support the theoretical contention that leases and debt are substitutes and is thus consistent with evidence from surveys of lending officers. There is some evidence, however, that firms do not view leases as displacing nonleasing debt on a dollar-for-dollar basis.

A possible model for the concerted allosteric transition in Escherichia coli aspartate transcarbamylase as deduced from site-directed mutagenesis studies.

Abstract: Aspartate transcarbamylase is stabilized in a low-affinity-low-activity state exhibiting no cooperativity by selective perturbation of the Glu-50-Arg-167 and Glu-50-Arg-234 interdomain salt bridges. Similarly, a high-affinity-high-activity state of the enzyme, retaining a significant amount of cooperativity, is obtained by perturbation of the interaction between Tyr-240 and Asp-271. In this work, we show that the rupture of the link between Tyr-240 and Asp-271 in the enzyme already lacking the interdomain salt bridges regenerates the homotropic cooperative interactions between the catalytic sites and substantially increases the activity and affinity of the enzyme for aspartate. These results suggest a possible relationship between these two sets of interactions for the establishment of the cooperative behavior of the enzyme. Another mutation, Glu-239 to Gln, introduced to perturb the Glu-239-Lys-164 and Glu-239-Tyr-165 interactions between the two catalytic subunits, is sufficient to "lock" the enzyme in the R state. These observations emphasize the importance of the interactions at the interface between the catalytic trimers in maintaining the T state of the enzyme and shed light on the role played by this pathway in the communication of homotropic cooperativity between the different sites. A model including all these findings, as well as the interactions stabilizing the T state or the R state in the presence of the natural substrates, is proposed.(ABSTRACT TRUNCATED AT 250 WORDS)

regular Languages Defined with Generalized Quantifiers

Abstract: We study an extension of first-order logic obtained by adjoining quantifiers that count with respect to an integer modulus. It is shown that the languages definable in this framework are precisely the regular languages whose syntactic monoids contain only solvable groups. We obtain an analogous result for regular ω-languages and establish some connections with complexity theory for fixed-depth families of circuits.

Treatment with sodium butyrate inhibits the complete condensation of interphase chromatin

Abstract: The effects of histone hyperacetylation on chromatin fiber structure were studied using direct observations with the electron microscope. Histone hyperacetylation was induced in HeLa cells by treatment with sodium butyrate, and the ultrastructure of control and of acetylated chromatin fibers examined after fixation at different stages of compaction. No differences between control and acetylated chromatin were seen when the fibers were partially unfolded (10 mM NaCl, 20 mM NaCl, 50 mM NaCl), but in 100 mM NaCl, control chromatin showed further compaction to the “30 nm” fiber, while hyperacetylated chromatin failed to undergo this final compaction step. These results strongly suggest that histone acetylation causes a moderate “relaxation” rather than complete decondensation of interphase chromatin fibers. The relationship of these findings to the increased DNase I sensitivity of acetylated chromatin, and to transcription and replication, is discussed.

Relationship between domain closure and binding, catalysis, and regulation in Escherichia coli aspartate transcarbamylase.

Abstract: Previous evidence, from both crystallographic and biochemical studies, has indicated that profound tertiary and quaternary changes in the structure of Escherichia coli aspartate transcarbamylase occur upon the binding of the bisubstrate analogue N-(phosphonoacetyl)-L-aspartate (PALA). In particular, within a single catalytic polypeptide chain, the aspartate binding domain relocates closer to the carbamyl phosphate binding domain, thereby resulting in a major reorganization of the interface between the two domains. Among the new interactions, salt bridges between Glu-50 and both Arg-167 and Arg-234 are formed. In the present study, site-directed mutagenesis is used to replace Glu-50 by glutamine in the catalytic chain. The Michaelis constant for aspartate of the mutant catalytic subunit is about 10-fold higher and the turnover number 10-fold lower than their respective counterparts in the wild-type catalytic subunit, whereas the dissociation constant for carbamyl phosphate is almost unchanged. For the holoenzyme, this substitution results in an 8-fold decrease in the specific activity, a 20-fold increase in the aspartate concentration that gives half of the maximal velocity, and a loss of cooperativity for both substrates. However, the mutant enzyme is not "frozen" in a low-affinity-low-activity conformation since PALA stimulates the activity severalfold and induces an increase in the sulfhydryl reactivity analogous to that of the wild-type enzyme. Together these results indicate that the stabilization of the aspartate binding domain near the carbamyl phosphate binding domain, through specific interdomain bridging interactions, is necessary for the high-affinity-high-activity configuration of the active site.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement Driven Instruction: A Closer Look.

Abstract: The author discusses conditions under which Measurement Driven Instruction might and might not produce its expected results. He considers how test stakes, Performance standards, and the nature of content assessment interrelate to influence the operation of MDI programs. In discussing instructional expectations and realities as they apply to MDI, he argues that under some conditions instruction driven by measurement measurement corrupt the measurement process.

A new approach to the synthesis of a protected 2-aminopurine derivative and its incorporation into oligodeoxynucleotides containing the Eco RI and Bam HI recognition sites

Abstract: A protected 2-aminopurine nucleoside suitable for incorporation into oligodeoxynucleotides using phosphite triester chemical synthesis procedures has been prepared via oxidation of a purine hydrazino derivative with silver (I) oxide. Five oligodeoxynucleotides containing Eco RI and Bam HI recognition sites have been prepared such that, in the double stranded form, the 2-aminopurine base has either a complementary thymine or cytosine nucleobase. The helix character and thermodynamic parameters for helix formation have been examined.

An oligodeoxynucleotide affinity column for the isolation of sequence specific DNA binding proteins

Abstract: A nucleic acid affinity matrix containing a short oligodeoxynucleotide ligand has been prepared as an example of a material which can be used for the rapid and effective isolation of sequence specific DNA binding proteins. Two complementary oligodeoxynucleotides have been employed, one of which contains a small 5'-spacer arm with a terminal thiol group. Using this terminal thiol group, the ligand can be covalently coupled to Tresyl-activated Sepharose 4B or Epoxy-activated Sepharose 6B via a thioether linkage. This approach allows the specific attachment of the nucleic acid ligand via its 5'-terminus to the insoluble matrix. The double stranded affinity material was obtained by annealing of the complementary DNA fragment. As an example, we have used an eicosomer affinity column containing the sequence d(GAATTC) for the isolation of the Eco RI restriction endonuclease. Using a single column, the enzyme could be isolated by eluting the column with a single step or multistep gradient of increasing salt concentration. The enzyme was purified to 75%-85% homogeneity with yields of 0.1 mg to 0.2 mg from 0.5 g of cell paste.

Serial rapists and their victims: reenactment and repetition.

Abstract: The major finding in this study of 41 serial rapists is the large numbers of reported and unreported victims. For over 1200 attempted and completed rapes, there were 200 convictions. The hidden rapes or earliest nonreported victims of these men as boys and adolescents were identified from their families, their neighborhood, and their schools. Examining the possible link between childhood sexual abuse and criminal behavior in this sample of 41 serial rapists, 56.1% were judged to have at least one forced or exploitive abuse experience in boyhood, as compared to a study of 2,972 college males reporting 7.3% experiencing boyhood sexual abuse. Looking within the abused samples, 56.1% of the rapists reported forced sex, compared to the college sample's 30.4%. Also, the rapist sample revealed higher rates of family member as abuser (48.4%), compared to 22.2% for the college sample. Retrospective reconstruction of the sexual activities and assertive behaviors of these men as boys reveals that 51% of the boys reenact the abuse as a preadolescent with their earliest victims being known to them (48% as neighborhood girls), family (25% as sisters), or girlfriend (25%). The onset of rape fantasies in midadolescence (mean age 16.9) crystalizes the earlier sexually initiated behaviors into juvenile behaviors of spying, fetish burglaries, molestations, and rapes. Repetition of these juvenile behaviors set their criminal patters on strangers--their next group of victims. To reduce victimization, serial rapists need to be identified early and stopped. This means acknowledging and reporting boy sexual abuse. This includes being sensitive to the reenactment behaviors noted in the initiated activities of abused children, which in turn need to be differentiated from peer play. Closer attention needs to be paid to families with incest behavior to insure that younger children are protected. Adolescents showing early repetitive juvenile delinquent behaviors must be assessed for physical and sexual abuse, and intervention must be planned to deal with the victimization. In the investigation and apprehension of serial rapists, law enforcement might pay closer attention to fetish burglaries and the spying, secretive behaviors that serve as the prototype for rape behavior.