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PubMed2004

An examination of jury verdicts for evidence of a similarity-leniency effect, an out-group punitiveness effect or a black sheep effect.

Archival data from cases adjudicated by jury in El Paso and Bexar County, Texas, were used to test whether a similarity-leniency effect, an out-group punitiveness effect, or a black sheep effect (BSE; J. M. Marques, V Y. Yzerbyt, & J. P. Leyens, 1988) influenced jury decisions. Defendant ethnicity, jury ethnic composition, and strength of evidence against the defendant were coded for 418 closed noncapital, felony cases to test their impact on trial verdicts and sentence lengths. Results indicated complex relations exist among juror and defendant characteristics and their influence on trial outcomes. No support was found for any of the theoretical models as predictors of jury decision-making. Strength of evidence was the most influential variable for both verdicts and length of sentences. Case strength, defendant ethnicity, and jury composition were related to sentence lengths.

Analysis of Variance↗

PubMed2003

Validity of two oral health-related quality of life measures.

OBJECTIVES: To assess the validity of the Oral Impacts on Daily Performance (OIDP) and the short form of the Oral Health Impact Profile (OHIP 14) in the UK. SETTING: Primary care department at a UK dental hospital. SAMPLE: Consecutive patients. METHOD: Cross-sectional comparison of impacts using OIDP and OHIP 14 against clinical findings, Global Oral Health Ratings and pain. RESULTS: A total of 179 patients participated (83.2% response rate). OIDP had weak face validity because it contained contingency questions. Both instruments were developed from the same theoretical model and appeared to have reasonable content validity. In regression analyses, the number of impacts detected by each measure and the total score using OHIP 14 were related to the presence of oral disease and inversely related to age. No suitable transformation could be found to allow regression analysis of OIDP total scores. OHIP 14 correlated more closely with Global Oral Health Ratings but both measures correlated similarly to the experience of pain (0.43 < r < 0.47). The correlation between OHIP and OIDP scores was +0.78. The use of a simple additive method for calculating the total OHIP 14 score did not compromise its validity. CONCLUSION: Both instruments have some validity as measures of Oral Health-Related Quality of Life (OHRQoL) among dental hospital patients. The superior face, criterion and convergent validity and greater amenability to analysis of OHIP 14 render it more suitable for questionnaire-based research and for comparing groups. The additive method may be used to calculate the total score for OHIP 14.

Activities of Daily Living↗

PubMed1992

Stimulus recognition and the mere exposure effect.

A meta-analysis of research on Zajonc's (1968) mere exposure effect indicated that stimuli perceived without awareness produce substantially larger exposure effects than do stimuli that are consciously perceived (Bornstein, 1989a). However, this finding has not been tested directly in the laboratory. Two experiments were conducted comparing the magnitude of the exposure effect produced by 5-ms (i.e., subliminal) stimuli and stimuli presented for longer durations (i.e., 500 ms). In both experiments, 5-ms stimuli produced significantly larger mere exposure effects than did 500-ms stimuli. These results were obtained for polygon (Experiment 1), Welsh figure (Experiment 2), and photograph stimuli (Experiments 1 and 2). Implications of these findings for theoretical models of the mere exposure effect are discussed.

Adult↗

PubMed1975

Annoyance, type and duration of postannoyance activity, and aggression: the "cathartic effect".

A series of experiments was conducted to elucidate the conditions conductive to a decrease in aggression following annoyance. The potential capacity of expression of aggression to bring about a reduction in the amount of subsequent aggression was of particular interest. This empirical concern was supplemented by tests of several influential and competing theoretical concepts dealing with the cathartic aspects of human aggressive behavior. Given the failure of such concepts to account for major portions of the data, an integrative theoretical model was proposed. experiment 1 evaluated the usefulness of the hydraulic, self-arousal, and dissipation of anger concepts in accounting for the earlier demonstrations of the cathartic effect. In a 2 x 3 x 2 design, half of the subjects were annoyed by a confederate, while the other half were treated neutrally. During the next stage (the interpolated period), a third of all subjects gave "shocks" to the confederate, another third simply waited, while the remaining third worked on mathematical problems. Orthogonal to the first two facotrs was the duration of the interpolated period (7 to 13 min). The main dependent measure was the number of shocks administered to the confederate in the final stage of the experiment. It was found that annoyed subjects gave more shocks than nonannoyed ones did, and that only the former were substantially affected by other manipulations. In the case of the annoyed wait and annoyed math subjects, the anger dissipation hypothesis correctly predicted that the mere passage of time would decrease the amount of subsequent aggression, presumably due to the action of homeostatic processes. The self-arousal hypothesis correctly predicted that the annoyed math subjects would give fewer shocks than the annoyed wait ones would. Since the subjects were engaged in an absorbing activity, the likelihood of their arousing themselves by ruminations about the preceding annoying incident was minimized, and the amount of subsequent aggression reduced. Yet, when annoyed subjects had given the confederate a moderate number of shocks in the interpolated period, they subsequently gave him fewer shocks than the 7-min annoyed wait and annoyed math subjects; this was the only outcome predicted correctly by the hydraulic model. In contrast, when a large number of shocks had been administered in the interpolated period, the amount of subsequent aggression was relatively high. The interpretation of the latter result in terms of an "adaption effect" was tested by further experiments.

Abreaction↗

PubMed2000

Beyond white and middle class: cultural variations in families--assessments, processes, and policies.

The goal of this special issue on cultural variations in families--assessments, processes, and policies--is to increase our understanding of families of different ethnic, racial, and class backgrounds. Articles in this issue represent a range of cultural groups, illustrate a pattern of both similarities and differences across groups, and reflect the recent emphasis on processes that account for variation in families of different ethnic backgrounds. The articles focus on strengths of families of different ethnic backgrounds in contrast to earlier deficit models. Finally, theoretical models that recognize within-group variability of different ethnic, racial, and cultural groups are illustrated in these articles.

Cultural Diversity↗

PubMed2005

Psychological and physical well-being during unemployment: a meta-analytic study.

The authors used theoretical models to organize the diverse unemployment literature, and meta-analytic techniques were used to examine the impact of unemployment on worker well-being across 104 empirical studies with 437 effect sizes. Unemployed individuals had lower psychological and physical well-being than did their employed counterparts. Unemployment duration and sample type (school leaver vs. mature unemployed) moderated the relationship between mental health and unemployment, but the current unemployment rate and the amount of unemployment benefits did not. Within unemployed samples, work-role centrality, coping resources (personal, social, financial, and time structure), cognitive appraisals, and coping strategies displayed stronger relationships with mental health than did human capital or demographic variables. The authors identify gaps in the literature and propose directions for future unemployment research.

Adaptation, Psychological↗

PubMed2004

Does establishing fidelity of treatment help in understanding treatment efficacy? Comment on Bellg et al. (2004).

Comments on the article by Bellg et al (see record 2004-18051-001). To test the effects of a behavioral change on specific health outcomes, the Behavior Change Consortium insists on strict adherence to fidelity at 5 steps in behavioral trials: study design, provider training, treatment delivery, treatment receipt, and enactment of treatment skills. The authors argue that the demand for fidelity at every step ignores 2 critical sets of factors: (a) there are few theoretically grounded empirical studies of the processes involved in successful transitions in this sequence and (b) trials with perfect fidelity absent a theoretical model of transitions will produce evidence for interventions that lack a conceptual basis for adaptation to differences among diseases, treatments, patients, practitioners, medical institutions, and cultures and that therefore cannot be implemented in clinical practice.

Benchmarking↗

PubMed2001

Fabry - Perot interference in a nanotube electron waveguide.

The behaviour of traditional electronic devices can be understood in terms of the classical diffusive motion of electrons. As the size of a device becomes comparable to the electron coherence length, however, quantum interference between electron waves becomes increasingly important, leading to dramatic changes in device properties. This classical-to-quantum transition in device behaviour suggests the possibility for nanometer-sized electronic elements that make use of quantum coherence. Molecular electronic devices are promising candidates for realizing such device elements because the electronic motion in molecules is inherently quantum mechanical and it can be modified by well defined chemistry. Here we describe an example of a coherent molecular electronic device whose behaviour is explicitly dependent on quantum interference between propagating electron waves-a Fabry-Perot electron resonator based on individual single-walled carbon nanotubes with near-perfect ohmic contacts to electrodes. In these devices, the nanotubes act as coherent electron waveguides, with the resonant cavity formed between the two nanotube-electrode interfaces. We use a theoretical model based on the multichannel Landauer-Büttiker formalism to analyse the device characteristics and find that coupling between the two propagating modes of the nanotubes caused by electron scattering at the nanotube-electrode interfaces is important.

Electronics↗

PubMed2006

Oscillations and variability in the p53 system.

Understanding the dynamics and variability of protein circuitry requires accurate measurements in living cells as well as theoretical models. To address this, we employed one of the best-studied protein circuits in human cells, the negative feedback loop between the tumor suppressor p53 and the oncogene Mdm2. We measured the dynamics of fluorescently tagged p53 and Mdm2 over several days in individual living cells. We found that isogenic cells in the same environment behaved in highly variable ways following DNA-damaging gamma irradiation: some cells showed undamped oscillations for at least 3 days (more than 10 peaks). The amplitude of the oscillations was much more variable than the period. Sister cells continued to oscillate in a correlated way after cell division, but lost correlation after about 11 h on average. Other cells showed low-frequency fluctuations that did not resemble oscillations. We also analyzed different families of mathematical models of the system, including a novel checkpoint mechanism. The models point to the possible source of the variability in the oscillations: low-frequency noise in protein production rates, rather than noise in other parameters such as degradation rates. This study provides a view of the extensive variability of the behavior of a protein circuit in living human cells, both from cell to cell and in the same cell over time.

Biological Clocks↗

PubMed2004

The nonlinear nature of friction.

Tribology is the study of adhesion, friction, lubrication and wear of surfaces in relative motion. It remains as important today as it was in ancient times, arising in the fields of physics, chemistry, geology, biology and engineering. The more we learn about tribology the more complex it appears. Nevertheless, recent experiments coupled to theoretical modelling have made great advances in unifying apparently diverse phenomena and revealed many subtle and often non-intuitive aspects of matter in motion, which stem from the nonlinear nature of the problem.

Animals↗

PubMed2006

Statistical pattern matching facilitates the design of polyvalent inhibitors of anthrax and cholera toxins.

Numerous biological processes involve the recognition of a specific pattern of binding sites on a target protein or surface. Although ligands displayed by disordered scaffolds form stochastic rather than specific patterns, theoretical models predict that recognition will occur between patterns that are characterized by similar or "matched" statistics. Endowing synthetic biomimetic structures with statistical pattern matching capabilities may improve the specificity of sensors and resolution of separation processes. We demonstrate that statistical pattern matching enhances the potency of polyvalent therapeutics. We functionalized liposomes with an inhibitory peptide at different densities and observed a transition in potency at an interpeptide separation that matches the distance between ligand-binding sites on the heptameric component of anthrax toxin. Pattern-matched polyvalent liposomes inhibited anthrax toxin in vitro at concentrations four orders of magnitude lower than the corresponding monovalent peptide, and neutralized this toxin in vivo. Statistical pattern matching also enhanced the potency of polyvalent inhibitors of cholera toxin. This facile strategy should be broadly applicable to the detection and neutralization of toxins and pathogens.

Animals↗

PubMed2005

Theoretical aspects of fluoride air contaminant formation in aluminium smelter potrooms.

The amount of particulate fluorides evolved from aluminium electrolysis cells is not entirely accounted for by the fluorides entrained in the anode gas. The largest additional source of particulate fluoride formation is by direct evaporation of fluorides into the anode gas stream and subsequent condensation on the drops of electrolyte generated in the process of bubble burst. A theoretical model was used for the calculation of the main physical parameters responsible for the formation of particle nuclei when the hot anode-gas is mixed with ambient air. The results of these calculations are in agreement with experimental observations reported in the literature. In particular, the size distribution, composition and morphology of the nano-particles support the theory of a vapour condensation mechanism under conditions of extreme supersaturation, but further studies are necessary.

Air Pollution, Indoor↗

PubMed2005

Surface-directed capillary system; theory, experiments and applications.

We present a capillary flow system for liquid transport in microsystems. Our simple microfluidic system consists of two planar parallel surfaces, separated by spacers. One of the surfaces is entirely hydrophobic, the other mainly hydrophobic, but with hydrophilic pathways defined on it by photolithographic means. By controlling the wetting properties of the surfaces in this manner, the liquid can be confined to certain areas defined by the hydrophilic pathways. This technique eliminates the need for alignment of the two surfaces. Patterned plasma-polymerized hexafluoropropene constitutes the hydrophobic areas, whereas the untreated glass surface constitutes the hydrophilic pathways. We developed a theoretical model of the capillary flow and obtained analytical solutions which are in good agreement with the experimental results. The capillarity-driven microflow system was also used to pattern and immobilize biological material on planar substrates: well-defined 200 microm wide strips of human cells (HeLa) and fluorescence labelled proteins (fluorescein isothiocyanate-labelled bovine serum albumin, i.e., FITC-BSA) were fabricated using the capillary flow system presented here.

Adsorption↗

PubMed2005

Half or full core hole in density functional theory X-ray absorption spectrum calculations of water?

We analyze the performance of two different core-hole potentials in the theoretical modeling of XAS of ice, liquid and gas phase water; the use of a full core-hole (FCH) in the calculations, as suggested by Hetenyi et al. [B. Hetenyi, F. De Angelis, P. Giamozzi and R. Car, J. Chem. Phys., 2004, 120(18), 8632], gives poor agreement with experiment in terms of intensity distribution as well as transition energies, while the half core hole (HCH) potential, in the case of water, provides a better compromise between initial and final state effects, leading to good agreement with the experimental data.

Gases↗

PubMed2006

On the physical nature of mesophases of guanosine gels.

The unusual columnar aqueous mesophases of self-assembled guanosine stacks, such as 2'-deoxyguanosine 5'-monophosphate and 2'-deoxyguanosine 3'-monophosphate, are analyzed in terms of a general theory of azimuthal correlations between the charged helices. This theory considers forces, specific to the helical structure of each macromolecule, which depend on the azimuthal orientations of the molecules about their long axes. More specifically, in determining the magnitudes and decay lengths of these helix specific forces we utilize the Kornyshev-Leikin theory of electrostatic interaction between helical macromolecules and quantitatively fit experimental data. Together with explaining a number of the observed features of these mesophases, several new effects are predicted. Possible limitations and developments of our theoretical model are discussed, as well as new experiments to test the implications of the theory.

Deoxyguanine Nucleotides↗

PubMed1991

Assembly of chick brain MAP2-tubulin microtubule protein. Analysis of tubulin subunit flux rates by immunofluorescence microscopy.

A filter-based immunofluorescence-microscopy method for obtaining microtubule lengths has been developed and evaluated. Kinetic constants and mean lengths obtained show close agreement with those obtained by complementary methods applied to chick brain MAP2-tubulin microtubule protein in NaCl-supplemented buffer. The filter-based method has been used to estimate tubulin subunit flux (Jon) resulting from isothermal dilution of microtubule populations to various free tubulin concentrations, (c). This experimental Jon(c) plot is significantly different from that predicted by a variety of theoretical models, but is consistent with a 'lateral cap' model of dynamic instability [Bayley, Schilstra & Martin (1990) J. Cell. Sci. 95, 33-48] adapted to accommodate the observed vectorial GTP hydrolysis.

Animals↗

PubMed1991

Kinetics of the specific binding of a second RNA polymerase to the standard bacterial-transposon-Tn3 bla promoter complex.

It was shown previously, that at moderate excess of RNA polymerase (RNAP) relative to DNA, the complex of the bla promoter from bacterial transposon Tn3 with RNAP is locked in an inactive, heparin-resistant, isomeric state which is not that of the 'open' complex. This 1:1 isomer can accommodate a second RNAP, which becomes tightly and specifically bound just upstream of the first RNAP [Duval-Valentin & Reiss (1990) Mol. Microbiol. 4, 1465-1475]. Both the resulting 2:1 complex and its antecedent 1:1 complex formed at excess of RNAP are immediately and permanently inhibited for transcription initiation. Using the gel-retardation technique, we investigate here the kinetics of formation and decay of the 2:1 complex under various experimental conditions. The data are consistent with pseudo-first-order kinetics at moderate excess of RNAP. The salt-dependence of rate and equilibrium constants has been analysed within the framework of the theoretical model described by Lohman, Dehaseth & Record [(1978) Biophys. Chem. 8, 281-294]. It was found that the salt-dependence is consistent with the existence of a transient intermediate during formation of the 2:1 complex, which forms rapidly on the time scale of its isomerization to the final 2:1 complex. The intermediate is characterized by the release of about seven cations from the 1:1 complex, one additional cation being released upon its final isomerization. Formation of the 2:1 complex at high excess of RNAP becomes inhibited, probably as a result of a 'bumping' effect of the complex by the enzyme, also observed with several other promoters. We conclude that formation of the 2:1 complex closely mimics that of the standard 1:1 complex, except that the final isomerization step to an 'open' complex is lacking. A mechanism of the formation of the 2:1 complex and of its role in transcription regulation of constitutive promoter by RNAP is proposed.

DNA Transposable Elements↗

PubMed1992

Importance of various antioxidant enzymes for cell stability. Confrontation between theoretical and experimental data.

A theoretical model was developed taking into account the production and destruction of oxygen-derived free radicals. The steady state of the system was derived by using the rate equations of these reactions, and the stability of the system was tested. In the simplified model, only one stable steady state was found. However, we know that glutathione peroxidase can be inhibited by hydroperoxides, and, when incorporated into the model, this effect led to a complex situation with the presence of some stable and some unstable domains according to the concentration of either the enzyme or the hydroperoxide. This qualitative description of the system was compared with experimental data on the protection given by three antioxidant enzymes, and concordance of data was found which allows some quantification of the system. A general view of the efficiency of the three antioxidant enzymes and of the stability of the system according to their concentrations could be produced.

Animals↗