A model for nonlinear viscoelastic mechanical responses of collagenous soft tissues

Experimental observations of the time-dependent mechanical responses of collagenous tissues have demonstrated behavior that deviates from standard treatments of linear or quasi-linear viscoelasticity. In particular, time-dependent deformation can be strongly coupled to strain level, and strain-rate independence can be observed under monotonic loading, even for a tissue with dramatic stress relaxation. It was postulated that this nonlinearity is fundamentally associated with gradual recruitment of individual collagen fibrils during applied mechanical loading. Based on previously observed experimental results for the time-dependent response of collagenous soft tissues, a model is developed to describe the mechanical behavior of these tissues under uniaxial loading. Tissue stresses, under applied strain-controlled loading, are assumed to be a sum of elastic and viscoelastic stress contributions. The relative contributions of elastic and viscoelastic stresses is assumed to vary with strain level, leading to strain- and time-dependent mechanical behavior. The model formulation is examined under conditions of monotonic loading at varying constant strain rates and stress-relaxation at different applied strain levels. The model is compared with experimental data for a membranous biological soft tissue, the amniotic sac, and is found to agree well with experimental results. The limiting behavior of the novel model, at large strains relative to the collagen recruitment, is consistent with the quasi-linear viscoelastic approach. © 2006 Materials Research Society.

EARLY MOTHER-INFANT RELATIONSHIPS OF MACACA-THIBETANA AT MT-EMEI CHINA

Quantitative data on early mother-infant relationships in the Tibetan macaque was collected during the first 23 weeks of infant life in spring, 1987, at Mt. Emei, China. During the first week of life, infants spent 98.3% of their time in ventroventral contact with their mothers. This contact rapidly decreased to 33.8% by the 4th week and thereafter to 0.85% by the 23rd week. Nipple contact decreased relatively slowly from 89.7% to 62.9% within the first 4 weeks of infant life and to 19.8% by the 23rd week. Ventrolateral and ventrodorsal contact appeared by the 2nd week, mean-while, maternal restraining behavior appeared, and reached a peak by the 3rd week. The mother neither encouraged nor discouraged her infant's independence during 4-8th weeks. Maternal rejection of the infant was first observed when the infant was 11 weeks old and continued thereafter.

Independence is elusive: set size effects on encoding precision in visual search.

Looking for a target in a visual scene becomes more difficult as the number of stimuli increases. In a signal detection theory view, this is due to the cumulative effect of noise in the encoding of the distractors, and potentially on top of that, to an increase of the noise (i.e., a decrease of precision) per stimulus with set size, reflecting divided attention. It has long been argued that human visual search behavior can be accounted for by the first factor alone. While such an account seems to be adequate for search tasks in which all distractors have the same, known feature value (i.e., are maximally predictable), we recently found a clear effect of set size on encoding precision when distractors are drawn from a uniform distribution (i.e., when they are maximally unpredictable). Here we interpolate between these two extreme cases to examine which of both conclusions holds more generally as distractor statistics are varied. In one experiment, we vary the level of distractor heterogeneity; in another we dissociate distractor homogeneity from predictability. In all conditions in both experiments, we found a strong decrease of precision with increasing set size, suggesting that precision being independent of set size is the exception rather than the rule.

Variation patterns of the mitochondrial 16S rRNA gene with secondary structure constraints and their application to phylogeny of cyprinine fishes (Teleostei : Cypriniformes)

The mitochondrial 16S ribosomal RNA (rRNA) gene sequences from 93 cyprinid fishes were examined to reconstruct the phylogenetic relationships within the diverse and economically important subfamily Cyprininae. Within the subfamily a biased nucleotide composition (A > T, C > G) was observed in the loop regions of the gene, and in stem regions apparent selective pressures of base pairing showed a bias in favor of G over C and T over A. The bias may be associated with transition-transversion bias. Rates of nucleotide substitution were lower in stems than in loops. Analysis of compensatory substitutions across these taxa demonstrates 68% covariation in the gene and a logical weighting factor to account for dependence in mutations for phylogenetic inference should be 0.66. Comparisons of varied stem-loop weighting schemes indicate that the down-weightings for stem regions could improve the phylogenetic analysis and the degree of non-independence of stem substitutions was not as important as expected. Bayesian inference under four models of nucleotide substitution indicated that likelihood-based phylogenetic analyses were more effective in improving the phylogenetic performance than was weighted parsimony analysis. In Bayesian analyses, the resolution of phylogenies under the 16-state models for paired regions, incorporating GTR + G + I models for unpaired regions was better than those under other models. The subfamily Cyprininae was resolved as a monophyletic group, as well as tribe Labein and several genera. However, the monophyly of the currently recognized tribes, such as Schizothoracin, Barbin, Cyprinion + Onychostoma lineages, and some genera was rejected. Furthermore, comparisons of the parsimony and Bayesian analyses and results of variable length bootstrap analysis indicates that the mitochondrial 16S rRNA gene should contain important character variation to recover well-supported phylogeny of cyprinid taxa whose divergences occurred within the recent 8 MY, but could not provide resolution power for deep phylogenies spanning 10-19 MYA. (c) 2008 Published by Elsevier Inc.

Structure optimization of field-plate AlGaN/GaN HEMTs

AlGaN/GaN high electron mobility transistors (HEMTs) on 6H-SiC with varying field-plate length and gate-drain spacing were fabricated and analyzed. The classical small signal FET model and the well-known ColdFET method were used to extract the small signal parameters of the devices. Though the devices with field plates exhibited lower better f(T) characteristic, they did demonstrate better f(max), MSG and power density performances than the conventional devices without field plate. Besides, no independence of DC characteristic on field-plate length was observed. With the increase of the field-plate length and the gate-drain spacing, the characteristic of f(T) and f(max), degraded due to the large parasitic effects. Loadpull method was used to measure the microwave power performance of the devices. Under the condition of continuous wave at 5.4 GHz, an output power density of 4.69 W/mm was obtained for device with field-plate length of 0.5 mu m and gate-drain length of 2 mu m. (c) 2006 Elsevier Ltd. All rights reserved.

Foundations of Actor Semantics

The actor message-passing model of concurrent computation has inspired new ideas in the areas of knowledge-based systems, programming languages and their semantics, and computer systems architecture. The model itself grew out of computer languages such as Planner, Smalltalk, and Simula, and out of the use of continuations to interpret imperative constructs within A-calculus. The mathematical content of the model has been developed by Carl Hewitt, Irene Greif, Henry Baker, and Giuseppe Attardi. This thesis extends and unifies their work through the following observations. The ordering laws postulated by Hewitt and Baker can be proved using a notion of global time. The most general ordering laws are in fact equivalent to an axiom of realizability in global time. Independence results suggest that some notion of global time is essential to any model of concurrent computation. Since nondeterministic concurrency is more fundamental than deterministic sequential computation, there may be no need to take fixed points in the underlying domain of a power domain. Power domains built from incomplete domains can solve the problem of providing a fixed point semantics for a class of nondeterministic programming languages in which a fair merge can be written. The event diagrams of Greif's behavioral semantics, augmented by Baker's pending events, form an incomplete domain. Its power domain is the semantic domain in which programs written in actor-based languages are assigned meanings. This denotational semantics is compatible with behavioral semantics. The locality laws postulated by Hewitt and Baker may be proved for the semantics of an actor-based language. Altering the semantics slightly can falsify the locality laws. The locality laws thus constrain what counts as an actor semantics.

Ben Bowen (Writers of Wales)

Chapman, T. R. Ben Bowen (Writers of Wales)(University of Wales Press, 2003) RAE2008

Growing up in a mainstream world: a retrospective enquiry into the childhood experiences of young adults with a physical disability.

Children with disabilities are at greater risk of developing mental health problems than their peers, yet the emotional well-being of this group is largely overlooked and there is scant literature about children with a mobility disability. This study examined the retrospective experiences of growing up with mobility disability. The sample comprised of 16-25 year olds with mobility disability. A thematic analysis, informed by grounded theory was used. Themes identified included a common socio educational journey, conflict between care and independence in school and the impact of being singled out because of disability out side school. The result was a range of psycho-social issues that affected participants view of themselves and the world around them. The study also looked at what the participants found helpful in dealing with the emotional impact of their disability. Whilst some sought help through talking therapies, others found involvement in disability sport was helpful.

Accents of Chopin anniversaries in territories annexed by Prussia

This article discusses the way in which the Chopin Year of 1910 was celebrated in Wielkopolska. It presents a script prepared in the nineteenth century and shows similarities with celebrations of Mickiewicz and other Polish heroes and artists. Invariably used in such commemorations was a “symbolic capital” that made it easier to create an intergenerational code, thereby disseminating knowledge of national culture and history. A significant role was played in 1910 by a centenary panel, which produced “Guidelines for popular Chopin celebrations” and also many occasional, popular materials. Chopin’s induction into the national pantheon involved the use of audio material (vocal and instrumental concerts), verbal material (articles, poems, lectures and brochures) and also a visual code (anniversary window stickers, tableaux vivants or tableaux illuminés). Illuminated pictures – recommended by a catalogue of slides produced in Poznań – stimulated the imagination of the masses and served as a guide through the composer’s life and work, and their impact was enhanced by a commentary. Most of the living pictures were probably inspired by Henryk Siemiradzki’s canvas Chopin grający na fortepianie w salonie księcia Radziwiłła [Chopin playing the piano in Prince Radziwiłł’s salon] and Józef Męcina Krzesz’s painting Ostatnie akordy Chopina [Chopin’s last chords]. This combination of codes made it possible to create a model adapted to the times and to the expectations of a mass audience. The Chopin anniversary, in which admiration was inseparably intertwined with manipulation, was a pretext for strengthening the national identity.

Dialogic Signals In Argumentative Discussions of Advanced Polish Learners Of English

The first part of the paper deals with characteristics of classroom interaction as a type of institutional talk in a conversational analytic perspective. Next, the thesis is discussed concerning developing learners' interactional competence to foster learner discursive independence in argumentative discussions in English as a foreign language. Finally, after a short review of dialogic signals, the article presents a preliminary analysis of selected dialogic signals: evaluating reformulations and piggybacking as the ways of achieving reciprocity in argumentative discussions.

Dialogic Signals In Argumentative Discussions of Advanced Polish Learners Of English

The first part of the paper deals with characteristics of classroom interaction as a type of institutional talk in a conversational analytic perspective. Next, the thesis is discussed concerning developing learners' interactional competence to foster learner discursive independence in argumentative discussions in English as a foreign language. Finally, after a short review of dialogic signals, the article presents a preliminary analysis of selected dialogic signals: evaluating reformulations and piggybacking as the ways of achieving reciprocity in argumentative discussions.

The Missionary pioneer, or, A brief memoir of the life, labours, and death of John Stewart, (man of colour) founder, under God of the mission among the Wyandotts at Upper Sandusky, Ohio / Published by Joseph Mitchell.

http://www.archive.org/details/missionarypionee00stewrich