Showing papers by "University at Buffalo published in 1988"

Theoretical stress strain model for confined concrete

Abstract: A stress‐strain model is developed for concrete subjected to uniaxial compressive loading and confined by transverse reinforcement. The concrete section may contain any general type of confining steel: either spiral or circular hoops; or rectangular hoops with or without supplementary cross ties. These cross ties can have either equal or unequal confining stresses along each of the transverse axes. A single equation is used for the stress‐strain equation. The model allows for cyclic loading and includes the effect of strain rate. The influence of various types of confinement is taken into account by defining an effective lateral confining stress, which is dependent on the configuration of the transverse and longitudinal reinforcement. An energy balance approach is used to predict the longitudinal compressive strain in the concrete corresponding to first fracture of the transverse reinforcement by equating the strain energy capacity of the transverse reinforcement to the strain energy stored in the concret...

A Cross-Linguistic Survey of the Grammaticization of Evidentiality

Abstract: Etat de la recherche dans le domaine des morphemes grammaticaux marqueurs de la modalite epistemique de " l'evidence " (indicateur de la source de l'information dans la proposition)

Coping, expectancies, and alcohol abuse: A test of social learning formulations.

Abstract: components of this approach, tests of a comprehensive social learning model of abuse have been lacking. The model proposed here postulates that alcohol abuse can be predicted from a causal chain that includes alcohol consumption and "drinking to cope" as proximal determinants and general coping skills and positive alcohol expectancies as more distal determinants. To evaluate this model in a way that permits simultaneous consideration of its multiple determinants and control for demo- graphic influences, path analytic techniques were applied to data from problem and nonproblem drinkers drawn from a general population sample. The hypothesized model accounted for significant variance in abuse status. Drinking to cope emerged as the most powerful predictor, exerting influence via direct and indirect pathways. Coping styles indicative of avoidance of emotion emerged as more important predictors of abuse than problem-focused coping. The predictive value of coping was moderated by alcohol expectancies such that avoidant styles of coping with emotion were predictive of abuse status only among drinkers expressing greater belief in alcohol's positive reinforcing proper- ties. These findings both support and refine the social learning perspective on alcohol abuse. Theoret- ical and treatment implications are considered. Social learning theory posits that people who exhibit abusive patterns of drinking differ from "healthy" drinkers in their abil- ity to cope with the demands of everyday life and in their beliefs about alcohol (Abrams & Niaura, 1987).~ According to this per- spective, deficiencies in more adaptive coping skills and positive expectancies about alcohol's effects operate independently and jointly to promote the use of drinking as a coping mechanism. Reliance on alcohol to cope should lead to heavier drinking and, over time, increase the risk of alcohol abuse. This perspective on the development and maintenance of alcohol abuse has heavily influenced the content, techniques, and goals of a range of alco- hol treatment programs. In particular, the teaching of general and alcohol-specific coping skills, and to a lesser extent the mod- ification of beliefs about the effects of alcohol, are integral com- ponents of various treatment approaches (e.g., social skills training). Despite its widespread influence in the treatment field, no comprehensive test of the social learning perspective has been conducted. The present study tests a causal model de-

Mechanical transduction in biological systems.

Abstract: Mechanical transduction, the transformation of cellular deformation into an electrochemical response, is essential to the survival of both cells and higher organisms. In the specialized sensory organs, mechanotransducers are responsible for the sensations of hearing, touch and vibration, local gravity, kinesthesis, and probably osmoreception. In the viscera, mechanoreception provides sensory feedback on organ volume and pressure. At the cellular level, mechanoreceptors are known to provide feedback for avoidance reactions in free-swimming protozoans and for the gravitational and tactile reactions of plants. Mechanotransducers are probably essential in regulating cell volume and cell division. The known properties of mechanotransducers can be accounted for by ion channels whose gating is controlled by membrane strain.

The Incommensurate Modulation of the 2212 Bi-Sr-Ca-Cu-O Superconductor

Abstract: The incommensurate modulation evident in the diffraction pattern of the superconductor Bi 2 Sr 3- x Ca x Cu 2 O 8+ y consists of almost sinusoidally varying displacements of up to 0.4A of the Bi and Sr atoms in the a -and c -directions of the unit cell, and of up to 0.3 A of the Cu atoms in the c direction only. Thus, a newly discovered feature of the Bi 2 Sr 3- x Ca x Cu 2 O 8+ y structure is sizable Cu displacement, which is related to static wave formation in the Cu-O sheets. Reported thermal parameters give evidence that similar distortions occur on cooling of the thallium-containing superconductors.

Perceptions of Postdrinking Female Sexuality: Effects of Gender, Beverage Choice, and Drink Payment1

Abstract: To examine the postulate that the drinking woman is viewed differently than her nondrinking counterpart, two experiments were conducted. In Study 1, 174 subjects completed an alcohol expectancy questionnaire that was modified to assess expected alcohol effects on another person: young man or young woman. The woman was perceived as being more sexual after drinking than was the man. These perceptions were also influenced by expected alcohol dosage, subjects' gender, and drinking experience. In Study 2, 176 subjects read a vignette depicting a woman having drinks with a man. To manipulate the stimulus woman's consumption and the drink payment arrangement, 8 versions of the vignette were employed: The woman was described as drinking cola or alcohol (beer, wine or whiskey) and as paying for her own drinks or allowing the man to “pick up the tab”. Subjects rated the drinking woman as significantly more aggressive, impaired, sexually available, and as significantly more likely to engage in foreplay and intercourse. Perceptions of her sexual disinhibition and likelihood of sex play were significantly enhanced if the man bought the drinks. Compared to their own perceptions of her, subjects estimated that her date would see her as significantly more disinhibited and socially skilled and as less impaired. The alcohol-drinking woman was also seen as less attractive than her cola-drinking counterpart. Practical implications regarding stereotypes about cross-gender drinking situations and theoretical implications regarding alcohol expectancy research are discussed.

The release of leukotrienes in the respiratory tract during infection with respiratory syncytial virus: role in obstructive airway disease.

Abstract: Samples of nasopharyngeal secretions from a group of 73 infants with bronchiolitis or upper respiratory illness alone during infection with respiratory syncytial virus were analyzed for leukotriene C4 (LTC4) content using a reverse-phase high-pressure liquid chromatography assay with confirmation by radioimmunoassay. Titers of respiratory syncytial virus (RSV)-specific IgE in nasopharyngeal secretion (NPS) specimens were determined using an enzyme-linked immunosorbent assay. The highest concentrations of LTC4 were found in the first 3 to 8 days after the onset of illness, and LTC4 was detectable in progressively lower concentrations in samples obtained up to 28 days after the onset of illness. LTC4 was detected in samples of NPS obtained in the acute phase of illness from 67% of infants with bronchiolitis due to RSV and in 33% of samples of NPS obtained during the same interval from infants with upper respiratory illness alone (p less than 0.025). Concentrations of LTC4 in children with bronchiolitis were 5-fold higher (1271 pg/ml) than the mean concentration of LTC4 in children with upper respiratory illness (224 pg/ml, p less than 0.02). LTC4 was detected in 83% of the children developing an RSV-IgE response and in 24% of subjects not developing an RSV-IgE response (p less than 0.001). Quantities of LTC4 measured in NPS were directly correlated with the magnitude of the RSV-IgE response in secretions (r = 0.33, p less than 0.02). These studies lend support to previous investigations suggesting that severe bronchiolitis due to RSV results from IgE-mediated hypersensitivity reactions to viral antigens, with release of chemical mediators of airway obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Stretch activated ion channels in ventricular myocytes.

Abstract: Patch-clamp recordings from ventricular myocytes of neonatal rats identified ionic channels that open in response to membrane stretch caused by negative pressures (1 to 6 cm Hg) in the electrode. The stretch response, consisting of markedly increased channel opening frequency, was maintained, with some variability, during long (>40 seconds) stretch applications. The channels have a conductance averaging 120 pS in isotonic KCl, have a mean reversal potential 31 mV depolarized from resting membrane potential, and do not require external Ca++ for activation. The channels appear to be relatively non-selective for cations. Since they are gated by physiological levels of tension, stretch-activated channels may represent, a cellular control system wherein beat-to-beat tension and/or osmotic balance modulate a portion of membrane conductance.

The origin of periodontal infections.

Abstract: Periodontal diseases are recognized as bacterial infections, and some forms are associated with specific organisms, such as Actinobacillus actinomycetemcomitans in juvenile periodontitis, and Bacteroides gingivalis and others in adult periodontitis. The source of the periodontal organisms, whether they are part of the indigenous or resident flora and overgrow to become opportunistic oral pathogens, or whether they are exogenous oral pathogens, is important to determine. The chain of periodontal infection, microbial agent(s) and their transmission, and host response are reviewed with respect to the role of A. actinomycetemcomitans in localized juvenile periodontitis and B. gingivalis in adult periodontitis. The present data lead us to hypothesize that some periodontal organisms may be exogenous pathogens.Prevention of periodontal diseases may be influenced by the knowledge of whether various forms are caused by opportunistic organisms or exogenous pathogens. If exogenous pathogens are responsible, preventi...

Characterization of collagenolytic activity from strains of Bacteroides gingivalis.

Abstract: Strains of B. gingivalis were shown to produce collagenolytic activity capable of dissolving reconstituted collagen (type I) fibrils and of cleaving the helical domain of types I. II and III collagens at 22° C. The catalytic activity was dependent on free thiol groups and on metal ions, as indicated by inhibition by thiol blocking reagents and metal chelators. The activity was associated with the bacterial cells and was not secreted to the medium. Under optimal conditions. 100 Units of collagenase per gram cell pellet (wet weight) were released by detergents such as Triton X-100 and SDS. Zymography of detergent extracts revealed that collagen-degrading strains, but not an inactive control strain (W), contained a discrete Mr 90 000 gelatin cleaving protease which may be identical to the collagenolytic enzyme. The initial attack on the helical domain of type I collagen occurred near the COOH-terminus. The a1 and a2 chains were cleaved at the same site, generating a major helical fragment consisting of three shortened (Mr 82 000) a-chains. Subsequent cleavages of this shortened collagen molecule resulted in generation of multiple fragments from the component a-chains in the Mr 60 000 to 6000 range. This cleavage pattern was clearly distinct from the characteristic 3/4–1/4 pattern produced by vertebrate collagenases. Type II and III collagens were also cleaved first near the COOH-terminus, generating fragments of similar size to those produced from type I collagen. In view of its ability to dissolve reconstituted collagen fibrils at 35°C and its ability to attack the helical domain of interstitial collagens in solution at 22°C, we suggest that this enzyme tentatively be classified as a true collagenase.

Actinobacillus Actinomycetemcomitans in the Pathogenesis of Human Periodontal Disease

Abstract: The present report reviews data implicating Actinobacillus actinomycetemcomitans in the etiology of human periodontal disease. Recent data are also presented relative to: (1) serological studies of this microorganism using monoclonal antibodies and the serodiagnosis of A. actinomycetemcomitans infections; (2) characterization of the serotype antigens; (3) studies of the serotype distribution of A. actinomycetemcomitans in extra-oral infections; and (4) examination of the correlation between A. actinomycetemcomitans colony morphology and fimbriae.

Molecular Mechanisms of Membrane Fusion

Abstract: Calcium-Induced Membrane Fusion: From Liposomes to Cellular Membranes.- Gel Phase Fusion of Dipalmitoyl Phosphatidylcholine Small Unilamellar Vesicles.- Structural Characterization of Lamellar Mg2+ Complexes of Dilauroylphosphatidic Acid Using 31P and 13C NMR.- Lipid Polymorphism, Lipid Asymmetry and Membrane Fusion.- Membrane Fusion Via Intermediates in L?/HII Phase Transitions.- The Influence of Polar Group Identity on the Interactions Between Phospholipid Bilayers.- Intrinsic Colloidal Attraction/Repulsion Between Lipid Bilayers and Strong Attraction Induced by Non-Adsorbing Polymers.- Mechanisms of Membrane Fusion in Acidic Lipid-Cation Systems.- Polar Interfacial Interactions, Hydration Pressure and Membrane Fusion.- Surface Tension, Hydration Energy and Membrane Fusion.- Interactions in Liposomal-Drug Delivery In Vivo and In Vitro.- Drug Delivery By Immunoliposomes.- Osmotic Forces and the Fusion of Biomembranes.- Fusion in Biological and Model Membranes: Similarities and Differences.- Early Steps in the Exocytosis of Secretory Vesicles in Mast Cells.- Electrofusion and Electrotransfection of Cells.- Pre-Selection of B-Lymphocytes by Antigen for Fusion to Myeloma Cells by Pulsed Electric Field (PEF) Method.- The Mechanism of Erythrocyte Ghost Fusion by Electric Field Pulses.- Water-Mediated Effects of PEG on Membrane Properties and Fusion.- Control of Cell Membrane Fusion by Lipid Composition.- Role of Phospholipid Asymmetry in Cellular Membrane Fusion.- Ultrastructural Studies of the Kinetics of Fusion.- pH Triggered Synthetic Peptides: Models for Viral Fusion Sequences.- Membrane Fusion in Model Systems for Exocytosis: Characterization of Chromaffin Granule Fusion Mediated By Synexin and Calelectrin.- Synexin, Calcium and the Hydrophobic Bridge Hypothesis for Membrane Fusion.- Molecular Mechanism of Protein-Mediated Low pH-Induced Membrane Fusions.- pH-Dependent Fusion of Vesicular Stomatitis Virus with Cells: Studies of Mechanism Based on an Allosteric Model.- Properties of a Viral Fusion Protein.- Parameters Affecting the Fusion of Viruses with Artificial and Biological Membranes.- Active Function of Membrane Receptors in Fusion of Enveloped Viruses with Cell Plasma Membranes.- `Entry' of Enveloped Viruses into Liposomes.- Fusion Activity of Influenza Virus and Reconstituted Viral Envelopes: Direct Evidence for Fusion in an Intracellular Acidic Compartment.- Kinetics and Extent of Fusion of Influenza Virus and Sendai Virus with Liposomes.- Strategies for the Investigation of Exocytotic Membrane Fusion.- Enzymatic Regulation of Membrane Fusion During Synchronous Exocytosis in Paramecium Cells.- Studies on the Structure and Function of the Asialoglycoprotein Receptor in the Cell, In Vitro and in Reconstituted Membranes.- Phosphorylation Events in Regulation of Exocytosis.- Geometric Topology of Membrane Fusion: From Secretion to Intercellular Junctions.- 'Slow Artifacts' in Assays of Lipid Mixing Between Membranes.- Why Fusion Assays Disagree.- Concentration Dependence of DPHpPC Fluorescence Lifetime: Photophysics and Utility for Monitoring Membrane Fusion.- Contributors.- Attendees.

Development of pulmonary vascular response to oxygen

Abstract: The ability of the pulmonary circulation of the fetal lamb to respond to a rise in oxygen tension was studied from 94 to 146 days of gestation. The unanesthetized ewe breathed room air at normal atmospheric pressure, followed by 100% oxygen at three atmospheres absolute pressure in a hyperbaric chamber. In eleven near-term lambs (132 to 146 days of gestation), fetal arterial oxygen tension (PaO2) increased from 25 +/- 1 to 55 +/- 6 Torr (mean +/- SE), which increased the proportion of right ventricular output distributed to the fetal lungs from 8 +/- 1 to 59 +/- 5%. In five very immature lambs (94 to 101 days of gestation), fetal PaO2 increased from 27 +/- 1 to 174 +/- 70 Torr, but the proportion of right ventricular output distributed to the lung did not change, 8 +/- 1 to 9 +/- 1%. In five of the near-term lambs, pulmonary blood flow was measured. It increased from 34 +/- 3 to 298 +/- 35 ml.kg fetal wt-1.min-1, an 8.8-fold increase. We conclude that the pulmonary circulation of the fetal lamb does not respond to an increase in oxygen tension before 101 days of gestation; however, near term an increase in oxygen tension alone can induce the entire increase in pulmonary blood flow that normally occurs after the onset of breathing at birth.

Minimum model error estimation for poorly modeled dynamic systems

Abstract: A novel strategy (which we call "minimum model error'* estimation) for postexperiment optimal state estimation of discretely measured dynamic systems is developed and illustrated for a simple example. The method is especially appropriate for postexperiment estimation of dynamic systems whose presumed state governing equations are known to contain, or are suspected of containing, errors. The hew method accounts for errors in the system dynamic model equations in a rigorous manner. Specifically, the dynamic model error terms in the proposed method do not require the usual Kalman filter-smoother process noise assumptions of zero-mean, symmetrically distributed random disturbances, nor do they require representation by assumed parameterized time series (such as Fourier series); Instead, the dynamic model error terms require no prior assumptions other than piecewise continuity. Estimates of the state histories, as well as the dynamic model errors, are Obtained as part of the solution of a two-point boundary value problem. The state estimates are continuous and optimal in a global sense, yet the algorithm processes the measurements sequentially. The example demonstrates the method and shows it to be quite accurate for state estimation of a poorly modeled dynamic system.

The dentist-patient relationship: perceived dentist behaviors that reduce patient anxiety and increase satisfaction

Abstract: Researchers asked 250 adults to respond to 25 dentist behaviors after receiving treatment. Positive reactions were recorded in response to ten behaviors perceived to be associated with anxiety reduction: specifically, empathy, friendliness, and communicativeness.

Isolation and characterization of a Neurospora glucose-repressible gene

Abstract: Using differential hybridization, the cDNA copy of a Neurospora gene coding for an abundant glucose-repressible mRNA (grg-1) has been isolated. The cDNA was used to clone the genomic copy, and both were sequenced. The cDNA is nearly full length and contains putative translational start and termination codons. Conceptual translation indicates that grg-1 mRNA could direct the synthesis of a 7,000 molecular weight polypeptide. The genomic clone, contained in an 1,888 bp PvuII fragment, encompasses the entire cDNA as well as 838 bp of 5' and 369 bp of 3' flanking sequence. Comparison of the cDNA and genomic clones revealed the presence of two short introns in potential protein-coding sequences. grg-1 message levels were found to increase within minutes following the onset of glucose deprivation and rise 50 fold during the first 90 min of derepression.

A Comparison of Different Treatments for Nocturnal Bruxism

Abstract: One hundred bruxers were evaluated for bruxing activity before, during, and after treatment with a portable electromyograph (EMG). A six-month post-treatment follow-up of bruxing activity was obtained. Experimental treatment groups consisted of diurnal biofeedback, nocturnal biofeedback, massed negative practice, and splint therapy. A no-treatment control group was included. The comparative efficacy of treatments was determined by analyses of variance.Both EMG-measured frequency of bruxing episodes and duration of bruxing activity decreased significantly for nocturnal biofeedback and splint therapy treatments but not for massed negative practice, diurnal biofeedback (relaxation), or the no-treatment control group. The two-week treatment effects were transient, and bruxing activity generally returned to baseline levels when treatment was withdrawn. These findings are consistent with the findings of previous researchers with regard to nocturnal biofeedback and splint therapy but differ from previous finding...