77 resultados para Convergence And Extension
em University of Queensland eSpace - Australia
Resumo:
In both Australia and Brazil there are rapid changes occurring in the macroenvironment of the dairy industry. These changes are sometimes not noticed in the microenvironment of the farm, due to the labour-intensive nature of family farms, and the traditionally weak links between production and marketing. Trends in the external environment need to be discussed in a cooperative framework, to plan integrated actions for the dairy community as a whole and to demand actions from research, development and extension (R, D & E). This paper reviews the evolution of R, D & E in terms of paradigms and approaches, the present strategies used to identify dairy industry needs in Australia and Brazil, and presents a participatory strategy to design R, D & E actions for both countries. The strategy incorporates an integration of the opinions of key industry actors ( defined as members of the dairy and associated communities), especially farm suppliers ( input market), farmers, R, D & E people, milk processors and credit providers. The strategy also uses case studies with farm stays, purposive sampling, snowball interviewing techniques, semi-structured interviews, content analysis, focus group meetings, and feedback analysis, to refine the priorities for R, D & E actions in the region.
Resumo:
The cadherin superfamily members play an important role in mediating cell-cell contact and adhesion (Takeichi, M., 1991. Cadherin cell adhesion receptors as a morphogenetic regulator. Science 251, 1451-1455). A distinct subfamily, neither belonging to the classical or protocadherins includes Fat, the largest member of the cadherin super-family. Fat was originally identified in Drosophila. Subsequently, orthologues of Fat have been described in man (Dunne, J., Hanby, A. M., Poulsom, R., Jones, T. A., Sheer, D., Chin, W. G., Da, S. M., Zhao, Q., Beverley, P. C., Owen, M. J., 1995. Molecular cloning and tissue expression of FAT, the human homologue of the Drosophila fat gene that is located on chromosome 4q34-q35 and encodes a putative adhesion molecule. Genomics 30, 207-223), rat (Ponassi, M., Jacques, T. S., Ciani, L., ffrench, C. C., 1999. Expression of the rat homologue of the Drosophila fat tumour suppressor gene. Mech. Dev. 80, 207-212) and mouse (Cox, B., Hadjantonakis, A. K., Collins, J. E., Magee, A. I., 2000. Cloning and expression throughout mouse development of mfat 1, a homologue of the Drosophila tumour suppressor gene fat [In Process Citation]. Dev. Dyn. 217, 233-240). In Drosophila, Fat has been shown to play an important role in both planar cell polarity and cell boundary formation during development. In this study we describe the characterization of zebrafish Fat, the first non-mammalian, vertebrate Fat homologue to be identified. The Fat protein has 64% amino acid identity and 80% similarity to human FAT and an identical domain structure to other vertebrate Fat proteins. During embryogenesis fat mRNA is expressed in the developing brain, specialised epithelial surfaces the notochord, ears, eyes and digestive tract, a pattern similar but distinct to that found in mammals. (c) 2005 Elsevier B.V. All rights reserved.
Resumo:
Study Design. Biomechanical study of unembalmed human lumbar segments. Objective. To investigate the effects of tensioning the lumbar fasciae ( transversus abdominis [TrA]) aponeurosis) on segment stiffness during flexion and extension. Summary of Background Data. Animal and human studies suggest that TrA may influence intersegmental movement via tension in the middle and posterior layers of lumbar fasciae ( MLF, PLF). Methods. Compressive flexion and extension moments were applied to 17 lumbar segments from 9 unembalmed cadavers with 20 N lateral tension of the TrA aponeurosis during: 1) static tests: load was compared when fascial tension was applied during static compressive loads into flexion-extension; 2) cyclic loading tests: load, axial displacement, and stiffness were compared during repeated compressive loading cycles into flexion-extension. After testing, the PLF was incised to determine the tension transmitted by each layer. Results. At all segments and loads (< 200 N), fascial tension increased resistance to flexion loads by similar to 9.5 N. In 15 of 17, fascial tension decreased resistance to extension by similar to 6.6 N. Fascial tension during cyclic flexion loading decreased axial displacement by 26% at the onset of loading (0 - 2 N) and 2% at 450 N ( 13 of 17). During extension loading, fascial tension increased displacement at the onset of loading ( 10 of 17) by similar to 23% and slightly (1%) decreased displacement at 450 N. Segment stiffness was increased by 6 N/mm in flexion (44% at 25 N) and decreased by 2 N/mm (8% at 25 N) in extension. More than 85% of tension was transmitted through the MLF. Conclusions. Tension on the lumbar fasciae simulating moderate contraction of TrA affects segmental stiffness, particularly toward the neutral zone.
Resumo:
The phrenic nerve enters the diaphragm at approximately embryonic day 12.5 (E12.5) in the mouse. The secondary nerve trunk advances along the centre of the diaphragm muscle and extends tertiary branches primarily towards the lateral side during normal embryonic development. In the present study we quantified the intramuscular neurite branching in the most ventral region of the diaphragm at E15.5 and E18.5 in wild-type mice, agrin knock-out mice (KOAG) and rapsyn knock-out mice (KORAP). KOAG and KORAP have decreased muscle contraction due to their inability to maintain/form acetylcholine receptor (AChR) clusters during embryonic development. Heterozygote mothers were anaesthetised via an overdose of Nembutal (30 mg; Boeringer Ingelheim, Ridgefield, CT, USA) and killed via cervical dislocation. There were increases in the number of branches exiting the medial side of the phrenic nerve trunk in KOAG and KORAP compared to wild-type mice, but not on the lateral side at E15.5 and E18.5. However, the number of bifurcations in the periphery significantly increased on both the medial and lateral sides of the diaphragm at E15.5 and E18.5 in KOAG and KORAP compared to control mice. Furthermore, neurites extended further on both the medial and lateral sides of the diaphragm at E15.5 and E18.5 in KOAG and KORAP compared to wild-type mice. Together these results show that the restriction of neurite extension and bifurcations from the secondary nerve trunk is lost in both KOAG and KORAP allowing us the opportunity to investigate the factors that restrict motoneuron behaviour in mammalian muscles.
Resumo:
As an alternative to traditional evolutionary algorithms (EAs), population-based incremental learning (PBIL) maintains a probabilistic model of the best individual(s). Originally, PBIL was applied in binary search spaces. Recently, some work has been done to extend it to continuous spaces. In this paper, we review two such extensions of PBIL. An improved version of the PBIL based on Gaussian model is proposed that combines two main features: a new updating rule that takes into account all the individuals and their fitness values and a self-adaptive learning rate parameter. Furthermore, a new continuous PBIL employing a histogram probabilistic model is proposed. Some experiments results are presented that highlight the features of the new algorithms.
Resumo:
Widely used ''purchasing power parity'' comparisons of per capita GDP are not true quantity indexes and are subject to systematic substitution bins. This bias may distort measurement of convergence and divergence. Extending Varian's nonparametric construction of a true index gives the set of true indexes, including the new Ideal Afriat Index. These indexes are utility-consistent and independent of arbitrary reference price vectors. We establish bounds on the dispersion of true multilateral indexes, hence bounds on convergence. International price indexes understate both true GDP dispersion and, where prices are converging over time, the rate of true quantity convergence.
Resumo:
To help understand the mechanisms of gene rearrangement in the mitochondrial (mt) genomes of hemipteroid insects, we sequenced the mt genome of the plague thrips, Thrips imaginis (Thysanoptera). This genome is circular, 15,407 by long, and has many unusual features, including (1) rRNA genes inverted and distant from one another, (2) an extra gene for tRNA-Ser, (3) a tRNA-Val lacking a D-arm, (4) two pseudo-tRNA genes, (5) duplicate control regions, and (6) translocations and/or inversions of 24 of the 37 genes. The mechanism of rRNA gene transcription in T. imaginis may be different from that of other arthropods since the two rRNA genes have inverted and are distant from one another. Further, the rRNA genes are not adjacent or even close to either of the two control regions. Tandem duplication and deletion is a plausible model for the evolution of duplicate control regions and for the gene translocations, but intramitochondrial recombination may account for the gene inversions in T. imaginis. All the 18 genes between control regions #1 and #2 have translocated and/or inverted, whereas only six of the 20 genes outside this region have translocated and/or inverted. Moreover, the extra tRNA gene and the two pseudo-tRNA genes are either in this region or immediately adjacent to one of the control regions. These observations suggest that tandem duplication and deletion may be facilitated by the duplicate control regions and may have occurred a number of times in the lineage leading to T. imaginis. T. imaginis shares two novel gene boundaries with a lepidopsocid species from another order of hemipteroid insects, the Psocoptera. The evidence available suggests that these shared gene boundaries evolved by convergence and thus are not informative for the interordinal phylogeny of hemipteroid insects. We discuss the potential of hemipteroid insects as a model system for studies of the evolution of animal rut genomes and outline some fundamental questions that may be addressed with this system.
Resumo:
Rhythmic movements brought about by the contraction of muscles on one side of the body give rise to phase-locked changes in the excitability of the homologous motor pathways of the opposite limb. Such crossed facilitation should favour patterns of bimanual coordination in which homologous muscles are engaged simultaneously, and disrupt those in which the muscles are activated in an alternating fashion. In order to examine these issues, we obtained responses to transcranial magnetic stimulation (TMS), to stimulation of the cervicomedullary junction (cervicomedullary-evoked potentials, CMEPs), to peripheral nerve stimulation (H-reflexes and f-waves), and elicited stretch reflexes in the relaxed right flexor carpi radialis (FCR) muscle during rhythmic (2 Hz) flexion and extension movements of the opposite (left) wrist. The potentials evoked by TMS in right FCR were potentiated during the phases of movement in which the left FCR was most strongly engaged. In contrast, CMEPs were unaffected by the movements of the opposite limb. These results suggest that there was systematic variation of the excitability of the motor cortex ipsilateral to the moving limb. H-reflexes and stretch reflexes recorded in right FCR were modulated in phase with the activation of left FCR. As the f-waves did not vary in corresponding fashion, it appears that the phasic modulation of the H-reflex was mediated by presynaptic inhibition of Ia afferents. The observation that both H-reflexes and f-waves were depressed markedly during movements of the opposite indicates that there may also have been postsynaptic inhibition or disfacilitation of the largest motor units. Our findings indicate that the patterned modulation of excitability in motor pathways that occurs during rhythmic movements of the opposite limb is mediated primarily by interhemispheric interactions between cortical motor areas.
Resumo:
Using the framework of communication accommodation theory the authors examined convergence and maintenance on evaluations of Chinese and Australian students. In Study 1, Australian students judged interactions between an Anglo-Australian. and another interactant who either maintained his or converged in speech style. Results indicated that participants were aware of convergence but that speaker ethnicity (Anglo-Australian, Chinese Australian or Chinese national) was a stronger influence on evaluations and future intentions to interact with the speaker In Study 2, Australian students judged Chinese speakers who maintained communication style or converged on interpersonal speech markers, intergroup markers, or both types of markers. Results indicated that the more participants defined themselves in intergroup terms, the more positively they judged intergroup convergence relative to interpersonal convergence and maintenance. This points to the importance of distinguishing between, convergence on interpersonal and intergroup speech markers, and underlines the role of individual differences in the evaluation of convergence.