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Biomedical subjects

W Claeys

Publications and source records attributed to W Claeys.

11 recordsLinked to original sources
PubMed2005

The kinetics of heat-induced structural changes of beta-lactoglobulin.

Heat-induced structural changes of beta-lactoglobulin were studied at temperatures ranging from 67.5 to 82.5 degrees C, and at pH 7.5. These changes were monitored by measurement of surface hydrophobicity, thiol availability, and protein solubility. Kinetic studies were conducted to quantitatively describe the contribution of hydrophobic and SH/SS interchange reactions to the thermal structural changes of beta-lactoglobulin. Results indicate that beta-lactoglobulin is sensitive to heat-induced interchange reactions with consequences for protein solubility. The extent of changes measured by the increase in surface hydrophobicity and the decrease in slow-reacting SH groups content could be described by a first-order fractional conversion model and were characterized by activation energy values of 233.9 +/- 8.6 and 148.2 +/- 6.7 kJ/mol, respectively. The break in the Arrhenius plot suggested in literature for beta-lactoglobulin denaturation was confirmed in this study only for the kinetics of exposed SH groups.

Disulfides↗
PubMed2000

Surface acoustic waves at the vacuum-thermoviscoelastic solid interface.

The present investigation concerns the propagation of surface waves at the vacuum-solid interface of a solid which is isotropic and thermoviscoelastic, i.e., for which the effects of heat conductivity need to be taken into account. Calculations show that, in addition to the Rayleigh wave, a thermal surface wave propagates that couples both the thermal and the elasticity effects. This latter wave is interpreted in terms of evanescent plane waves. The displacement field associated with this wave is calculated and interpreted. Some experimental results are also presented.

Acoustics↗
PubMed1995

Organic material concentration in auditory outer hair cells measured by laser interferometry.

Outer hair cells (OHC) of the mammalian cochlea are quasicylindrical cells of different length, which play a major role in hearing at threshold. Their particular shape allows the use of a noninvasive laser interferometric technique of isolated cells in vitro in order to measure the organic material concentration (OMC), hence the density of each cell body. In most (95%) of the OHCs isolated from the same guinea pig, when the cell diameter is normalized, the results show that the cell body OMC does not vary with cell length. In different animals, the respective normalized OMC mean values can vary between 70 kg/m3 and 103 kg/m3. A few OHCs with morphological particularities often possess cell body OMCs > 103 kg/m3. The results of the interferometric measurements in isolated OHCs confirm that density variations in the cell bodies are not involved in a sound frequency coding. The in vitro OMC variations of the OHCs could be related to the isolation procedure; however, they could also correlate with actual in vivo OMC variations.

Animals↗
PubMed1990

The generality of mental addition models: simple and complex addition in a decision-production task.

Recently, Widaman, Geary, Cormier, and Little (in press) offered a general componential model for simple and complex addition. In the present study, the generalizability of this model to very complex addition problems and to production task performance was tested. We investigated addition-production performance using a new research paradigm, the decision-production task. The paradigm was used to assess the reaction times of 16 adults to 100 single-digit addition problems (Experiment 1) and to very complex three-digit addition problems (Experiment 2). Generally, the results give evidence for the basic assumptions of the Widaman et al. model. Some of the results, however, demonstrate that short-term memory load factors and strategy choices also have important effects on complex addition-production performance. Furthermore, the results of both experiments indicate that, in production tasks, the nature of the elementary search/compute process can be characterized as a memory-retrieval process and that the decision-production paradigm is a valuable alternative to the classical verbal production paradigm.

Adult↗
PubMed1981

Research findings on the nature of constructs in schizophrenics.

Using a personal construct theory approach, Radley (1974) proposes a theoretical view about the nature and genesis of schizophrenic thought disorder. In this study, we replicate some results of previous studies on which Radley relies and we test some implications of his view. A test, consisting of the four possible combinations of elicited and supplied constructs and elicited and supplied elements was administered on group of schizophrenics, part of them being thought disordered (TD), part of them being not thought disordered (NTD) at the moment of testing and on a matched group of normals. An additional test was administered in order to obtain a maldistribution score. Our findings confirm most of the characteristics of the TD and NTD phase in schizophrenics, as proposed by Radley and they suggest some additions to that view. Moreover, they call for some changes in the scoring system of the Grid Test for Schizophrenic Thought Disorder (Bannister & Fransella, 1967) by using the Element Consistency, Social Agreement and maldistribution scores and Intensity and Differentiation scores of only the retest.

Adult↗
PubMed1978

Field independence and recognition of trait names in an incidental learning paradigm.

Field-dependent individuals are known to be superior to field-independent individuals at recognizing socially relevant material in an incidental learning paradigm. The present study tested the hypothesis that this superiority is moderated by the target-relatedness of distractors. The stimuli were trait names. To assess recognition memory a recognition list was used with distractors differing in degrees of relatedness to the targets. Results indicate that the relationship of field-dependence to false recognition of distractor traits is moderated by the target-relatedness of the latter.

Cognition↗
PubMed1976

Field-dependence and stability of self-view.

Contrary to Witkin's opinion, field-dependent individuals are expected to show higher stability of self-view than field-independent individuals. 73 Belgian second-year university students were submitted to the Group Embedded Figures Test. The Five Personality Factor Test measuring extraversion, friendliness, emotional instability, conscientiousness and general culture, was administered to each student for self-description (self-report) and to both parents for description of the student (mother's report and father's report). The decrease of correlation between self-report and parent's report as a function of the degree of student's field-independence supports the author's hypothesis. Results are interpreted in terms of closer attention of field-independent individuals to relevant cues.

Behavior↗
PubMed1976

The influence of some parental characteristics on children's primary abilities and field independence: a study of adopted children.

The Children's Embedded Figures Test and measures of V, P, N and S abilities were administered to 5-7-year-old Belgian children (33 boys and 36 girls) adopted early in life. These child variables were correlated with the main factorial dimensions of the adoptive parents' answers on the Parental Attitude Research Instrument and on Buehler's Life Goals Inventory and with the adoptive mother's child-rearing practices, determined through an interview. The PARI dimensions were unrelated to children's test performances. Reinforcement of competition and independence, an interview variable, was significantly related to several ability measures and to the CEFT, especially in girls. The significant correlations of some LGI dimensions with boys' and/or girls' primary abilities were interpreted by referring to the influence on the development of children's abilities of a future-oriented attitude toward learning and memory and of a warm parent-child interaction.

Adoption↗