Mini-Review; Stress Genes: An Introductory Overview

Molecular sequence data, made available in the last 15 years or so, have led to the classification of living cells into three phylogenetic domains: Bacteria, Archaea, and Eucarya. All the organisms that have been tested belonging to either domain were capable of mounting a stress response with essentially the same characteristics, regardless of the stressor. The protagonists in the cell's stress response are the stress genes and their protein products. Some of the latter are molecular chaperones. Under physiological conditions, these chaperones aid other cellular proteins to fold properly and achieve a native -functional- configuration, and to translocate from the place of synthesis to the cell's locale in which they will operate. In a stressed cell, the stress proteins that are chaperones protect other molecules from denaturation and help those partially damaged to regain a functional configuration. Thus, cell death is avoided and recovery is enhanced. The study of stress genes and proteins has progressed considerably in organisms belonging to the domains Bacteria and Eucarya. Less is known about the archaeal stress genes. Here, research with an organism from the Archaea is discussed, focusing on the stress genes of the hsp70 (dnaK) locus. Future perspectives for basic and applied research within the health sciences and biotechnology industries are presented.     

WORKING MEMORY CAPACITY DISSOCIATES LEXICAL AND SENTENTIAL CONTEXT EFFECTS

Abstract— Semantically associated and unassociated word pairs were embedded in normal meaningful sentences and in sentences that were semantically anomalous throughout The influence of lexical context was isolated via comparison of responses to the second words of the associated and unassociated pairs. The influence of sentence-level context was isolated by comparing responses to the same words in the two sentence types Subjects of high, medium and low working memory capacity (as evaluated by the reading span test) showed modulations of event-related brain potentials in response so lexical context. In contrast, only the high- and medium-capacity groups were responsive to purely sentence-level semantic context. The results demonstrate that sentential context influences the processing of words in intermediate sentence positions at normal reading speeds but that the on-line utilization of this context is more demanding of working memory than single-word contexts.     

Measurement and the interpretation of quantum mechanics and relativity theory

The axiomatic approaches of quantum mechanics and relativity theory are compared with approaches in which the theories are thought to describe readings of certain measurement operations. The usual axioms are shown to correspond with classes of ideal measurements. The necessity is discussed of generalizing the formalisms of both quantum mechanics and relativity theory so as to encompass more realistic nonideal measurements. It is argued that this generalization favours an empiricist interpretation of the mathematical formalisms over a realist one.     

An alternative assessment of children's comprehension of relative clauses

Methodological difficulties are identified in the assessment of children's comprehension of relative clauses (RCs) by means of the standard acting-out procedure. An alternative experimental task is proposed which attempts to minimize these difficulties while exploring the advantages of the acting-out technique. An experiment is reported in which Portuguese-speaking 3- to 6-year olds were tested by means of this alternative task. The results show children being affected by both the position and the focus of the RC in the same way adults have been reported to be and an error analysis suggests that most of children's difficulties can be ascribed to memory overload while RCs are processed as noun modifier sentences. These results contradict the view that there are developmental differences with regard to the way sentences with RCs are parsed and that processing load induces errors particularly manifested in right-branching subject focus sentences. Developmental changes taking place between the ages of 3 and 6 are considered and questions are raised concerning development from the age of 5.The research reported here was carried out while the author read for the PhD degree at the University of London. The writing up of this paper was financially supported by a postdoctoral grant from the Brazilian Research Council (CNPq: 302103-86.4).     

Report of the ACA Ethics Committee: 1993–1994

The activities of the American Counseling Association (ACA) Ethics Committee are reviewed for the year 1993–1994. Summary data of ethical complaints and formal inquiries received during the year are presented followed by a brief discussion of trends noted. Updated information about the revision of the ACA Ethical Standards and the Policies and Procedures for Processing Complaints of Ethical Violations is also provided.     

Intuitive Perceptions of Decision-making Strategy: Naive Assessors' Concepts of Integrative Complexity

Although there are measurable differences in integrative complexity among solutions that individuals generate in dealing with problems, it is uncertain to what extent people comprehend, recognize, and have preferences among different levels of complexity. Integrative complexity is a function of differentiation (the perception of several attributes within, or perspectives about, a topic) and integration (combining the differentiated characteristics in an interactive or synthesizing solution). The current paper reports two experiments dealing with how university students perceive, interpret, and choose among solutions differing in complexity. Experiment 1 showed that subjects accurately rated the complexity of described solutions differing along the continuum, but that their assessment of their own responses differed from the results of expert scoring. Their self-estimated complexity was highly correlated with their preferences, and preferred complexity was reliably higher than either expert- or self-assessed complexity of subject-generated solutions. Subjects were able to hypothesize quite accurately about environmental and endogenous factors likely to affect complexity. Experiment 2 found that in response to problem scenarios, solutions selected as being potentially most effective were consistently more complex than solutions that participants considered themselves most likely to use. The idea of complexity seems to be intuitively recognizable and understandable by untrained subjects: They can and do distinguish among problem solutions (self-generated or presented) that vary on that dimension, and are able to assess accurately the effects of relevant variables. Such subjects also share the bias shown by experts in favour of the superiority of more complex approaches.     

Beyond belief bias: Reasoning from conceptual structures by mental models manipulation

Mental models constitute an alternative to the rule-based systems in the explanation of human reasoning (Johnson-Laird, 1983). In this paper, we claim that the concept of believability generally used to categorize content and context effects is of little use within a semantic theory. Thus, we propose the use of categories that are directly extracted from subjective relations among concepts within the reasoning problem. We demonstrate that manipulations based on this kind of categorization produce predictable patterns of responses in reasoning problems. We present two experiments to test our predictions, using conditional and syllogistic reasoning problems, and in both cases, we demonstrate the influence of conceptual knowledge not only in natural contexts, but also in experimentally created artificial contexts.     

Text Comprehension Training for Disabled Readers: An Evaluation of Reciprocal Teaching and Text Analysis Training Programs

Forty-six reading disabled adolescents were randomly assigned to one of three 25-hr instructional programs. Two programs provided training in expository text comprehension, and a third offered training in academic problem solving and organizational and study skills (an alternative treatment control). One reading comprehension program was designed to remediate a deficient knowledge base, forcing disabled readers to elaborate and further process new text knowledge, focusing on both specific informational content in a text and knowledge of text structure per se. The second program was patterned after the Palincsar and Brown (1984) reciprocal teaching techniques and focused on training four text comprehension strategies used by skilled comprehenders. Both the “knowledge-base” and the “strategy” training approaches were associated with significant improvement in disabled readers' comprehension skills, although training effects did not generalize across all aspects of reading comprehension performance. Strategy-trained readers applied the trained strategies with equal success on instructed and uninstructed text materials, providing strong evidence of transfer of learning. Knowledge-base readers also demonstrated successful transfer of specifically trained procedures (semantic mapping, text analysis) to unfamiliar text. In both programs, the best outcomes were obtained when specific strategies and operations were targeted for training.     

Validation of a full body 3-D dynamic linked segment model

In studies related to human movement, linked segment models (LSM's) are often used to quantify forces and torques, generated in body joints. Some LSM's represent only a few body segments. Others, for instance used in studies on the control of whole body movements, include all body segments. As a consequence of the complexity of 3-dimensional (3-D) analyses, most LSM's are restricted to one plane of motion. However, in asymmetric movements this may result in a loss of relevant information. The aim of the current study was to develop and validate a 3-D LSM including all body segments. Braces with markers, attached to all body segments, were used to record the body movements. The validation of the model was accomplished by comparing the measured with the estimated ground reaction force and by comparing the torques at the lumbo-sacral joint that resulted from a bottom-up and a top-down mechanical analysis. For both comparisons, reasonable to good agreement was found. Sources of error that could not be analysed this way, were subjected to an additional sensitivity analysis. It was concluded that the internal validity of the current model is quite satisfactory.