Infant Rule Learning: Advantage Language,or Advantage Speech?

Infants appear to learn abstract rule-like regularities (e.g., la la da follows an AAB pattern) more easily from speech than from a variety of other auditory and visual stimuli (Marcus et al., 2007). We test if that facilitation reflects a specialization to learn from speech alone, or from modality-independent communicative stimuli more generally, by measuring 7.5-month-old infants' ability to learn abstract rules from sign language-like gestures. Whereas infants appear to easily learn many different rules from speech, we found that with sign-like stimuli, and under circumstances comparable to those of Marcus et al. (1999), hearing infants were able to learn an ABB rule, but not an AAB rule. This is consistent with results of studies that demonstrate lower levels of infant rule learning from a variety of other non-speech stimuli, and we discuss implications for accounts of speech-facilitation.     

The human mandible: Lever,link, or both?

Hylander ('78) recently published important new data on bite force in humans, and showed that the human mandible cannot function purely as a link during incisal biting. He concluded instead that the mandible acts as a lever. Reexamination of Hylander's data suggests that the mandible cannot function purely as a lever either, and in fact it probably functions simultaneously as both lever and link during incisal biting.     

The Ecosystem: Model or Metaphor?

Industrial ecology offers an original way of looking at economic activities. The approach is based on an analogy between certain objects studied by the science of ecology (ecosystems, metabolisms, symbiosis, biocenosis, etc.) and industrial systems. However, this analogical relationship raises difficulties due to the various interpretations to which it is open. Although there is agreement regarding its heuristic function, the analogy can nevertheless be understood either as a model or as a metaphor. The present article first attempts to show how models differ from metaphors. It then sets out to justify the epistemological relevance of this distinction for industrial ecology research. The reflection should thus contribute to clarifying the debate on the (supposed or desired) role of analogy in the field of industrial ecology and heighten the interest this field of investigation represents for implementing sustainable development.     

The origins of entasis: illusion, aesthetics or engineering?

A typical characteristic of columns in Doric temples is entasis; a slight convexity in the body of a column. Often, and particularly in guide-books, it is suggested that entasis is intended to compensate for an illusion of concavity in columns with truly straight sides. We have investigated whether any such visual illusion exists, both in parallel sided and in tapering columns in a series of experiments, finding little evidence to support any illusion-compensation theory. Further, we explored the possibility that entasis was employed for purely aesthetic reasons, but the results do not support this conclusion. Finally, evidence supporting an engineering role for entasis is presented.     

The euryarchaeotes, a subdomain of Archaea, survive on a single DNA polymerase: fact or farce?

Archaea is now recognized as the third domain of life. Since their discovery, much effort has been directed towards understanding the molecular biology and biochemistry of Archaea. The objective is to comprehend the complete structure and the depth of the phylogenetic tree of life. DNA replication is one of the most important events in living organisms and DNA polymerase is the key enzyme in the molecular machinery which drives the process. All archaeal DNA polymerases were thought to belong to family B. This was because all of the products of pol genes that had been cloned showed amino acid sequence similarities to those of this family, which includes three eukaryal DNA replicases and Escherichia coli DNA polymerase II. Recently, we found a new heterodimeric DNA polymerase from the hyperthermophilic archaeon, Pyrococcus furiosus. The genes coding for the subunits of this DNA polymerase are conserved in the euryarchaeotes whose genomes have been completely sequenced. The biochemical characteristics of the novel DNA polymerase family suggest that its members play an important role in DNA replication within euryarchaeal cells. We review here our current knowledge on DNA polymerases in Archaea with emphasis on the novel DNA polymerase discovered in Euryarchaeota.     

The effects of whole body vibration on humans: dangerous or advantageous?

The effects of whole body vibration (WBV) have been studied extensively in occupational medicine. In particular, it has been shown that when the body undergoes chronically to whole body vibrations spinal degeneration is likely to be one of the deleterious outcomes. Low back pain has been shown to be the leading major cause of industrial disability in the population under the age of 45 years and has been linked to whole body vibration exposure encountered in some industrial settings. Whole body vibration has been recently purposed as an exercise intervention suggesting its effectiveness in increasing force-generating capacity in lower limbs and low back. It has also been reported to be an effective non-pharmacological intervention for patients with low back pain. Relatively short exposure to whole body vibration has been also shown to increase the serum levels of testosterone and growth hormone. The combined effects on the neuromuscular system and endocrine system seem to suggest its effectiveness as a therapeutic approach for sarcopenia and possibly osteoporosis. Due to the danger of long-term exposure to whole body vibration, it is important to develop safe exercise protocols in order to determine exercise programs for different populations.     

Temporal Learning and List-Level Proportion Congruency: Conflict Adaptation or Learning When to Respond?

The current report presents a temporal learning account as a potential alternative to the conflict adaptation account of list-level proportion congruent effects in the Stroop paradigm. Specifically, retrieval of information about response times on previous trials influences a participant''s preparedness to respond at a similar time on following trials. First, an adaptation of the Parallel Episodic Processing (PEP) model is presented, and a list-level effect is produced with a temporal learning mechanism. Next, linear mixed effect model analyses show that temporal learning biases are present in list-level proportion congruent data. A non-conflict experiment is then presented in which a list-level effect is observed with a contrast, rather than congruency, manipulation. Analyses of the experimental and simulated data could not, however, provide a clear picture of whether temporal learning was the sole contributor to the list-level proportion congruent effect. These results do, however, demonstrate that caution is warranted when interpreting list-level proportion congruent effects.     

The randomized controlled trial: gold standard, or merely standard?

The randomized controlled trial (RCT) is not a gold standard: it is a good experimental design in some circumstances, but that's all. Potential shortcomings in the design and implementation of RCTs are often mentioned in passing, yet most researchers consider that RCTs are always superior to all other types of evidence. This paper examines the limitations of RCTs and shows that some types of evidence commonly supposed to be inferior to all RCTs are actually superior to many. This has important consequences for research methodology, for quality of care in clinical medicine, and--especially--for research funding policy. Because every study design may have problems in particular applications, studies should be evaluated by appropriate criteria, and not primarily according to the simplistic RCT/non-RCT dichotomy promoted by some prominent advocates of the evidence-based medicine movement and by the research evaluation guidelines based on its principles.     

The GM debate: science or scaremongering?

Many conversations on genetic modification over the past few years have begun with the words 'I'm not a scientist, but...' They usually go on to say they do not follow the scientific detail, but it doesn't seem right to tamper with genes. The media and pressure groups have fuelled the fire with emotive terms like 'Frankenstein food', 'genetic pollution' and 'mutant crops'. There are important lessons here, which are as much about people and society as they are about science.     

The human mandible: Lever or link?

The mammalian mandible, and in particular the human mandible, is generally thought to function as a lever during biting. This notion, however, has not gone unchallenged. Various workers have suggested that the mandible does not function as a lever, and they base this proposition on essentially two assertions: (1) the resultant of the forces produced by the masticatory muscles always passes through the bite point; (2) the condylar neck and/or the temporomandibular joint is unsuited to withstand reaction forces during biting. A review of the electromyographic data and of the properties of the tissues of the temporomandibular joint do not support the non-lever hypothesis of mandibular function. In addition, an analysis of the strength of the condylar neck demonstrates that this structure is strong enough to withstand the expected reaction force during lever action. Ordinarily the human mandible and the forces that act upon it are analyzed solely in the lateral projection. Moments are then usually analyzed about the mandibular condyle; however, some workers have advocated taking moments about other points, e.g., the instantaneous center of rotation. Obviously it makes no difference as to what point is chosen since the moments about any point during equilibrium conditions are equal to zero. It is also useful to analyze the forces acting on the mandible in the frontal projection, particularly during unilateral biting. The electromyographic data suggest that during powerful unilateral molar biting the resultant adductor muscle force is passing between the bite point and the balancing (non-biting side) condyle. Therefore, in order for this system to be in equilibrium there must be a reaction force acting on the balancing condyle. This suggests that reaction forces are larger on the balancing side than on the working side, and possibly explains why individuals with a painful temporomandibular joint usually prefer to bite on the side of the diseased joint.     

The Opalinid Infusorians: Flagellates or Ciliates?

SUMMARY. The controversial question of the affinities of the enigmatic opalinids is discussed in the light of recent findings and with regard for modern ideas concerning characters of most significance in the phylogeny of various major protozoan groups. Metcalf's "protociliate" hypothesis still retains a high popularity although many of the factors supporting it have been adequately disproven during the past 20 years. The "ciliate-" and "flagellate-like" characteristics of the Opalinidae are listed and reviewed.
Considered to be one of the most significant of mastigophoran features is the "symmetrigenic" mode of fission, a character generally disregarded in the past. Coupled with nuclear monomorphism and a syngamous reproductive cycle the type of division presents a very strong argument in favor of closer affinities with the zooflagellates than with the ciliates. It is stressed that the opalinids are highly differentiated forms, not likely primitive or ancestral for any major group of protozoa, which have had a long evolutionary history of their own. Grassé's recent erection of a new super-order in the Zoomastigophora to contain the family Opalinidae is defended and commended.