The role of symmetry in the post-buckling behaviour of structures.

Symmetry plays an integral role in the post-buckling analysis of elastic structures. We show that the post-buckling response of engineering systems with given symmetry properties can be described using a preselected set of buckling modes. Therefore, the main original contribution of this paper is to prove the existence of these influential buckling modes and reveal some insights about them. From an engineering point of view, this study leads to the possibility of reducing computational effort in the analysis of large-scale systems. Firstly, symmetry groups for nonlinear elastic structural problems are discussed. Then, we invoke Curie's principle and describe the relationship between these groups and related pre-buckling and linear buckling deformation patterns. Then, for structural systems belonging to a given symmetry group, we re-invoke Curie's principle for describing the relationship between linear buckling modes and post-buckled deformation of the structure. Subsequently, we furnish a simplified asymptotic description which is obtained by projecting the equilibrium equations onto the subset of the most representative modes. As examples, classic bifurcation problems including isotropic and composite laminate panels under compression loading are investigated. Finally, the accuracy and computational advantages given by this new approach are discussed.

OLAF: standardization of international olfactory tests.

Developed in the 1990 s, the "Sniffin 'Sticks" test for the assessment of olfactory threshold, odor identification and discrimination has become a widely used tool both in clinical and research settings. Originally pencil-and-paper documented, it may now be applied using a computer program. The "Filemaker" based software "OLAF" guides the examiner through any user-defined arrangement of the test battery, stores all data in a database, and offers results sheets to be printed out for convenience. The royalty-free program may be downloaded from http://www.tu-dresden.de/medkhno/riechen_schmecken/olaf.zip as a runtime solution application. It is currently available in four languages (English, French, German, and Italian) which can be toggled by a single mouse click, and is suitable for Windows as well as Apple platforms. In conclusion, the currently described software is expected to further facilitate and standardize olfactory testing with the "Sniffin' Sticks" test battery.

Olfactory sensitivity in early-stage Parkinson patients affected by more marked unilateral disorder.

Two groups of subjects, 6 medicated Parkinson patients at an early stage of disease and affected by more marked right unilateral disorder and 12 normal elderly people, were examined on matching and naming olfactory tasks. On the former, subjects had to recognize among four previously sniffed odours, while on the latter they had to label an odour by choosing among four alternatives proposed by the examiner. Stimuli were administered to both nostrils. Analysis indicated that Parkinson patients were less efficient with the left nostril in the matching task, supporting the hypothesis of a larger compromise in the nostril contralateral to the side of the body more affected by the disease. Such a difference was not observed for the elderly people. Data are discussed with reference to the loss of dopamine in Parkinson patients.

Remembering spatial locations: effects of material and intelligence.

The aim of the present work was to test some of the criteria for automaticity of spatial-location coding claimed by Hasher and Zacks, particularly individual differences (as intelligence invariance) and effortful encoding strategies. Two groups of subjects, 15 with mental retardation (Down Syndrome, mean chronological age, 20.9 yr.; mean mental age, 11.6 yr.) and 15 normal children (mean age, 11.5 yr.), were administered four kinds of stimuli (pictures, concrete words, nonsense pictures, and abstract words) at one location on a card. Subsequently, subjects were presented the items on the card's centre and were required to place the items in their original locations. Analysis indicated that those with Down Syndrome scored lower than normal children on the four tasks and that stimuli were better or worse remembered according to their characteristics, e.g., their imaginability. Results do not support some of the conditions claimed to be necessary criteria for automaticity in the recall of spatial locations as stated by Hasher and Zacks.

Olfactory deficits in Down subjects: a link with Alzheimer disease.

Two groups of subjects, 14 young (ages 20 to 31 years) and 14 adults (ages 32 to 54 years), both groups with Down Syndrome, were examined on a matching and naming olfactory task. On the former, subjects were required to recognize among four a previously sniffed odour, while on the latter they had to label an odour by choosing among four alternatives provided by the examiner. Analysis indicated that the adults with Down Syndrome scored worse than the young group on both tasks and that the impairment of the two groups was more pronounced on the matching task. On considering the similarity between the neurodegenerative brain pathology exhibited by Alzheimer patients and Down subjects and a recent observation that the former show pathological changes also in the olfactory epithelium (neuritic plaques and neurofibrillary tangles), these two olfactory tasks could represent a useful noninvasive diagnostic method.

Olfactory deficits in elderly subjects and Parkinson patients.

Two groups of subjects, 8 Parkinson patients and 16 normal elderly people, were examined on a matching and a naming olfactory task. On the former, subjects had to recognize among four a previously sniffed odour, while on the latter they had to label an odour by choosing among four alternatives proposed by the examiner. Analysis indicated different trends for the two groups, Parkinson patients being more efficient in naming than in matching, and the elderly people showing the opposite pattern. Data are discussed with reference to the loss of dopamine in Parkinson patients and the decline of memory processes in elderly people.

Interference with visual short-term memory.

Working memory (Baddeley and Hitch 1974) incorporates the notion of a visuo-spatial sketch pad; a mechanism thought to be specialized for short-term storage of visuo-spatial material. However, the nature and characteristics of this hypothesized mechanism are as yet unclear. Two experiments are reported which examined selective interference in short-term visual memory. Experiment 1 contrasted recognition memory span for visual matrix patterns with that for visually presented letter sequences. These two span tasks were combined with concurrent arithmetic or a concurrent task which involved manipulation of visuo-spatial material. Results suggested that although there was a small, significant disruption by concurrent arithmetic of span for the matrix patterns, there was a substantially larger disruption of the letter span task. The converse was true for the secondary visuo-spatial task. Experiment 2 combined the span tasks with two established tasks developed by Brooks (1967). Span for matrix patterns was disrupted by a visuo-spatial task but not by a secondary verbal task. The converse was true for letter span. These results suggest that the impairment in short-term visual memory resulting from secondary arithmetic reflects a small general processing load, but that the selective interference due to mode of processing is by far the stronger effect. Results are interpreted as being entirely consistent with the notion of a specialized visuo-spatial mechanism in working memory.

Hemispheric differences in odour recognition.

Two experiments were designed in order to study hemispheric differences in odour recognition in normal subject. In the first experiment subjects first smelled an odour and then a visual stimulus (a picture or a word related or unrelated to the odour) was flashed either to the left or to the right hemisphere for 150 milliseconds. Subjects had to press a key if the two stimuli (olfactory and visual) matched and another key if they did not. Reaction time analysis showed that the responses were faster when the second stimulus (either picture or word) was presented to the right hemisphere. In a second experiment the first stimulus was auditory rather than olfactory. Subjects were instructed to listen to names of odorants and then to respond to pictures or written names as in the first experiment. In this case a left hemisphere advantage emerged, presumably related to the priming of the left hemisphere by the auditorially presented verbal stimulus.

Cognition and olfaction: a review.

Examines research in cognitive psychology, which has in the past paid little attention to the olfactory modality. But there is now a significant body of literature on the role of the olfactory system in memory and cognition. Human beings possess an excellent ability to detect and discriminate odors, but they typically have great difficulty in identifying particular odorants. This results partly from the use of an improverished and idiosyncratic language to describe olfactory experiences, which are normally encoded either in a rudimentary sensory form or as part of a complex but highly specific biographical episode. Consequently, linguistic processes play only a very limited role in olfactory processing, whereas hedonic factors seem to be of considerable importance.

Localization of polypeptides in frog virus 3 by radioiodination technique.

Frog virus 3 is an amphibian icosahedral deoxyribovirus which replicates in the cytoplasm of infected cells. The radioiodination of purified virions using the enzyme lactoperoxidase has shown that the major component of the structural proteins is only partially exposed through the lipoprotein membrane that constitutes the outer layer of the icosahedral capsid.