Showing papers by "Stony Brook University published in 1984"

The Spatial Theory of Voting: An Introduction

Abstract: Preface 1. Spatial voting models: the behavioural assumptions 2. The unidimensional spatial voting model 3. A two-dimensional spatial model 4. A general spatial model of candidate competition 5. The influence of candidate characteristics and abstention on election outcomes 6. Voting on budgets 7. Models of voter uncertainty 8. Institutions 9. Empirical testing of the spatial theory of elections 10. Concluding observations References Answers to selected problems Index.

Growth regulation of a cellular tumour antigen, p53, in nontransformed cells.

Abstract: Many transformed cells in culture have been found to express elevated levels of a cellular tumour antigen, termed p53. This protein has also been implicated in the regulation of cellular growth. For these reasons experiments were designed to examine the expression of p53 as quiescent cultures of nontransformed 3T3 fibroblasts were stimulated to reenter the cell cycle. Synchronous populations of cells were obtained by releasing a culture from density-dependent inhibition of growth with the addition of fresh serum. Steady-state levels of p53 protein and mRNA were measured as a function of time after addition of serum to quiescent cultures and the rate of synthesis of p53 protein was analysed at a number of time points. The results, reported here, demonstrate an increase in the synthesis and steady-state levels of p53 protein and mRNA prior to DNA synthesis in late G1, and suggest a role for p53 in the progression of cells from a growth-arrested state to an actively dividing state.

Wave diffraction due to areas of energy dissipation

Abstract: A parabolic model for calculating the combined refraction/diffraction of monochromatic linear waves is developed, including a term which allows for the dissipation of wave energy. The coefficient of the dissipation term is related to a number of dissipative models. Wave calculations are performed for a localized area of dissipation, based on a friction model for a spatial distribution of rigid vertical cylinders. The region of localized dissipation creates a shadow region of low wave energy, which may have important implications for the response of neighboring shore lines.

Lariat RNA's as Intermediates and Products in the Splicing of Messenger RNA precursors

Abstract: The splicing of messenger RNA precursors in vitro proceeds through an intermediate that has the 5' end of the intervening sequence joined to a site near the 3' splice site. This lariat structure, which has been characterized for an adenovirus 2 major late transcript, has a branch point, with 2'-5' and 3'-5' phosphodiester bonds emanating from a single adenosine residue. The excised intervening sequence retains the branch site and terminates in a guanosine residue with a 3' hydroxyl group. The phosphate group at the splice junction between the two exons originates from the 3' splice site at the precursor.

Computing and organizations: what we know and what we don't know

Abstract: Un examen de la litterature sur les effets du calcul dans les organisations revele que ces effets sont plus compliques et divers que ceux pris en charge traditionnellement

Mantle-derived Archaean monozodiorites and trachyandesites

Abstract: Geochemical data on monzodiorites and trachyandesites from the Rainy Lake area in Ontario which are strongly enriched in large-ion lithophile elements (LILE) are presented. It is concluded that they are derived by direct melting of the mantle at depths of less than 50 km in either anhydrous or hydrous conditions. Their rare earth element abundances and initial Nd-143/Nd-144 ratios suggest that their mantle sources were enriched in LILE shortly before melting. The monzodiorites-trachyandesites and their granodioritic derivatives may comprise up to 20 percent of the exposed igneous rocks in the Rainy Lake region and Vermilion District. If these rocks are as abundant in other Archaean terranes, a significant part of the early continental crust could have formed by direct melting of LILE-enriched mantle.

On the curvature of piecewise flat spaces

Abstract: We consider analogs of the Lipschitz-Killing curvatures of smooth Riemannian manifolds for piecewise flat spaces. In the special case of scalar curvature, the definition is due to T. Regge; considerations in this spirit date back to J. Steiner. We show that if a piecewise flat space approximates a smooth space in a suitable sense, then the corresponding curvatures are close in the sense of measures.

Predicting Supreme Court Cases Probabilistically: The Search and Seizure Cases, 1962-1981

Abstract: The overwhelming concensus of Fourth Amendment scholars is that the Supreme Court's sea and seizure cases are a mess. This article proposes that the confusion arises from the manner in which the cases were studied, not from the decisions themselves. A legal model with variables that me the prior justification of the search, the nature of the intrusion, and a few mitigating circumstance used to explain the Court's decisions on the reasonableness of a given search or seizure. The parameters are estimated through probit.The results show that the search and seizure cases are much more ordered than had commonly been believed. Virtually all of the estimates are as expected. Additionally, the Court is shown to act favorably toward the federal government than toward the states. Preliminary analysis suggests the model has predictive as well as explanatory value.

Class size and college students' evaluations of teachers and courses: A closer look

Abstract: A systematic analysis of extant studies reveals, on average, a very weak inverse association between the size of class enrollment in a college course and students' overall evaluation of the course and its teacher, as well as between class size and evaluations of specific instructional dimensions pertaining to the instructor's skill in presenting material and communicating information. Larger inverse associations are typically found between class size and evaluations of specific instructional dimensions pertaining to the instructor's interactions and interrelationships with students. This pattern of findings is consistent with the accumulating evidence that the instructional dimensions of the first set have greater importance for students in forming their global opinions of teachers and courses than do those of the second set. The further finding in some studies of a negative curvilinear (roughly U-shaped) relationship between class size and evaluations is noted and discussed. Implications for the validity of teacher evaluations are considered and the related question of whether class size “biases” these evaluations is explored.

Similarity in gene organization and homology between proteins of animal picomaviruses and a plant comovirus suggest common ancestry of these virus families

Abstract: The amino acid sequences deduced from the nucleic acid sequences of several animal picornaviruses and cowpea mosaic virus (CPMV), a plant virus, were compared. Good homology was found between CPMV and the picornaviruses in the region of the picornavirus 2C (P2-X protein), VPg, 3C pro (proteinase) and 3D pol (RNA polymerase) regions. The CPMV B genome was found to have a similar gene organization to the picornaviruses. A comparison of the 3C pro (proteinase) regions of all of the available picornavirus sequences and CPMV allowed us to identify residues that are completely conserved; of these only two residues, Cys-147 and His-161 (poliovirus proteinase) could be the reactive residues of the active site of a proteinase with analogous mechanism to a known proteinase. We conclude that the proteinases encoded by these viruses are probably cysteine proteinases, mechanistically related, but not homologous to papain.

Improvement Of Oligonucleotide-Directed Site-Specific Mutagenesis Using Double-Stranded Plasmid DNA

Abstract: Conditions which gave a high yield of oligonucleotide-directed site specific mutagenesis were obtained with use of the lpp gene of Escherichia coli cloned in the versatile expression plasmid vector, pIN-II. This plasmid (5.6-kb) was digested by PstI followed by exonuclease (Klenow fragment of DNA polymerase I) to remove a portion of the gene for β-lactamase. Another sample was digested by Xbal which cuts at a unique site in the pIN-II vector, and EcoRI to remove the portion of the lpp gene to be mutagenized. Both fragments were mixed with a synthetic oligonucleotide (the mutagen) and the mixture was denatured at 100°C for 3 min, followed by gradual cooling to reanneal. The mixture of renatured DNA was treated with the Klenow fragment of DNA polymerase I plus deoxynucleotide triphosphates in the presence of T4 ligase, and ampicillin-resistant transformants were isolated. In the case of a single base substitution, the yield of the desired mutant was as high as 13%. The present method can be applied to any gene cloned in a plasmid vector and is more convenient and simpler than the method using an M13 phage vector, since the mutated gene can be expressed directly from the plasmid vector used for the mutagenesis.

The Placement and Misplacement of You-Are-Here Maps

Abstract: A theory of spatial problem solving led to the prediction that the ease of use of you-are-here maps would depend upon where they were placed in relation to the terrain. Two experiments were perform...

Defense Mechanisms of Termites

Abstract: For predators of all sizes, termite colonies are dangerous but well-stocked pantries. The success of termites over the last 150 million years is due in large part to the development of elaborate architectural, behavioral, morphological, and chemical strategies for colony defense. Indeed, the literature on termite defense mechanisms has grown from a handful of chemical and observational studies to several hundred references in the last fifteen years. Among these are comprehensive reviews on chemical defenses of termite soldiers (70, 71, 74, 75), defense mechanisms and enemies of termites (25, 40), morphology and ultrastructure of termite defense glands (98), and the chemical systematics of termite exocrine secretions (76). In addition, isopteran defenses are portrayed in relation to those of other arthropods in an excellent monograph by Blum (10) and in a recent review by Pasteels et al (66). This review focuses on mechanical and chemical defense mechanisms of individual termites. The text presents the mechanical and chemical defense modes of workers and soldier termites in an analytical fashion. To complement this presentation, a comprehensive table is provided in which known defense strategies, chemicals, and habitats are arranged phylogenetic ally for all ter­ mites for which literature citations were available through March 1983. This table is designed to facilitate the location of relevant literature on the defensive mechanisms and ecology of any given taxon, and it fills a conspicuous void in the review literature to date. The importance of predators (14, 25, l00a), mound morphology, and behavioral ecology (19, 20, 57) in understanding how defenses are successful in an evolutionary ecological sense are not stressed. The bias of this review is chemical, and the author regrets omissions or

Choice in a self-control paradigm: Quantification of experience-based differences.

Abstract: Previous quantitative models of choice in a self-control paradigm (choice between a larger, more-delayed reinforcer and a smaller, less-delayed reinforcer) have not described individual differences. Two experiments are reported that provide additional quantitative data on experience-based differences in choice between reinforcers of varying sizes and delays. In Experiment 1, seven pigeons in a self-control paradigm were exposed to a fading procedure that increased choices of the larger, more-delayed reinforcer through gradually decreasing the delay to the smaller of two equally delayed reinforcers. Three control subjects, exposed to each of the small-reinforcer delays to which the experimental subjects were exposed, but for fewer sessions, demonstrated that lengthy exposure to each of the conditions in the fading procedure may be necessary in order for the increase to occur. In Experiment 2, pigeons with and without fading-procedure exposure chose between reinforcers of varying sizes and delays scheduled according to a concurrent variable-interval variable-interval schedule. In both experiments, pigeons with fading-procedure exposure were more sensitive to variations in reinforcer size than reinforcer delay when compared with pigeons without this exposure. The data were described by the generalized matching law when the relative size of its exponents, representing subjects' relative sensitivity to reinforcer size and delay, were grouped according to subjects' experience.

Oil field brines as ore-forming solutions

Abstract: Analyses of oil field brines from the Pleasant Bayou in the upper Texas Gulf Coast and the Rayleigh Field in central Mississippi were used to calculate the pH of the brines under reservoir conditions by assuming equilibrium with the reservoir mineral assemblages. The calculated pH values are less than 5.7 for the Pleasant Bayou brines at 138 degrees C and 787 bars and 4.3 (+ or -0.3) for the Rayleigh Field brines at 130 degrees C and 390 bars. Typical water-rock interactions have been investigated by theoretical evaluation of the thermodynamic consequences of the reactions of a hypothetical low-pH oilfield brine with quartz sandstone and dolostone aquifers that contain about 3 percent K-feldspar, 0.2 percent muscovite, and 0.01 percent pyrite by volume. The correlation of lead-rich (Southeast Missouri and Laisvall, Sweden) and zinc-rich (upper Mississippi Valley and East Tennessee) deposits with sandstone and dolostone aquifers, respectively, suggests that the reaction capacity of sandstone is more efficiently exhausted than that of dolostone. Importance in explaining geochemical characteristics of base-metal sulfide ore deposits. --Modified journal abstract.

Anatomical and physiological substrates of event-related potentials. Two case studies.

Abstract: Because an excellent tutorial introduction to the anatomical and physiological substrates of event-related potentials (ERPs) is available (Goff et al.. 1978), our objective in this chapter is not a general tutorial review. Rather, we intend to consider in detail the anatomical and physiological substrates of two classes or families of ERPs that have been the subject of intense investigation in recent years: (a) the auditory “ N I P ~ complex” and (b) P300 and related “endogenous” potentials. Our hope is that such a “case study” approach to ERP substrates will not only provide the reader with a thorough review of recent research findings, but will also provide a critical analysis of both the theoretical and empirical foundations of inferences about the neural substrates of ERPs. Our consideration of each family of potentials will consist of (a) a brief descriptive introduction, including the identifying characteristics of the potentials under consideration and the experimental conditions under which they can be obtained; (b) a detailed consideration of the different types of evidence that have been used to formulate and

Crystal structure and cation distribution in titanomagnetites (Fe (sub 3-x) Ti x O 4 )

Abstract: A systematic study of the crystal structure of titanomagnetites was undertaken to characterize the effects of composition and quenching temperature on the cation distribution. Powder specimens ranging in composition from pure magnetite to a slightly nonstoichiometric ulvrispinel were synthesized at temperatures between 930 and 1350'C. Several specimens quenched from 1350'C were later annealed at 800"C for up to 95 days. Unit-cell parameters were determined by X-ray diffraction, and saturation magnetization values were measured at room temperature on a vibrating sample magnetometer. The oxygen coordinate, thermal parameters, and sublattice magnetizations were determined from neutron difraction data using profile refinement techniques. No significant diferences were found in the unit-cell parameters or magnetization resulting from different synthesis temperatures or annealing, and no change was observed in the oxygen positional parameters following annealing. Ti occupies only octahedral sites in all specimens. Temperature factors increase markedly with Ti content, indicating static positional disorder due to mixing of Fe and Ti on octahedral sites. Values of the saturation magnetization and individual sublattice magnetic moments are consistent with the cation distribution model of Akimoto and do not support models that propose a quenchable, temperature-dependent Fe2*-Fe3* distribution. Diffuse scattering in the neutron diffraction patterns suggests the presence of short-range order, possibly involving octahedral cations, but no long-range order inconsistent with space group Fd3m was found. Systematic trends in the oxygen position and unit-cell parameter as a function of composition may be influenced bv octahedral cation interactions.

Influence of algal and suspended sediment concentrations on the feeding physiology of the hard clam Mercenaria mercenaria

Abstract: Short-term laboratory feeding experiments were conducted to determine the response of the hard clam Mercenaria mercenaria (L.) (32 mm in mean shell length) to increasing sediment concentrations. Clams were fed mixed suspensions of Pseudoisochrysis paradoxa (50 and 150 cells μl-1) and bottom sediments (0 to 44 mg l-1). Algal ingestion rate deelined with increasing sediment loads. This resulted primarily from a reduction in clearance rate, which declined by 0.08 l h-1 g-1 (1.3%) for every 1 mg l-1 increase in sediment load. This reduction was of similar magnitude for juvenile (13 mm) clams. At the algal concentrations tested, pseudofaeces production was intermittent and inconspicuous below about 10 mg silt l-1. Loss of algae in pseudofaeces increased with increasing sediment loads; however, even at the highest silt and algal concentrations, clams lost a maximum of only 18% of the algae cleared from suspension. Thus, pseudofaeces production is not expected to cause significant loss of algal food at the sediment concentrations normally encountered in the natural environment (≦ ca 40 mg silt l-1). Absorption rate of total organic matter remained constant, at least up to silt concentrations of 20 mg l-1. Experiments using dual 51Cr:14C-formaldehyde-labelled sediment indicated that clams were able to counteract the dilution of algae by absorbing a considerable fraction (21 to 22%) of detrital sedimentary organics. Absorption efficiency of pure P. paradoxa ranged from 82% at 50 cells μl-1 to 58% at 150 cells μl-1. Integration of physiological rate measurements suggests that at moderate to high algal concentrations (≧300 μg Cl-1), growth improvement by the addition of silt, documented in mussels, surf clams and oysters, is unlikely to occur in M. mercenaria. It is suggested that a suspension-feeding bivalve's success in maximizing its energy gain in a turbid environment depends on the combination of two features: a high selection efficiency and a high rate of pseudofaeces production. It is proposed that species which regulate ingestion primarily by producing pseudofaeces are better adapted to cope with high suspended sediment loads than species such as M. mercenaria, which control ingestion mainly by reducing clearance rate.