177,866 research outputs found
Assessment of musculoskeletal stress marker development in the hand
No full textThe analysis of musculoskeletal stress marker (MSM) development is a commonly employed tool in osteological surveys and is used to infer patterns of occupational activity and societal organisation in archaeological populations. Although the majority of research into upper limb MSMs has focused on the bones of the arm, the bones of the hand have been conspicuous by their absence. This is likely to be due to methodological issues surrounding the study of hand bones and a presumed lack of variation in MSM development in this area. To date, there have been no systematic studies investigating the presence and variation in MSM morphology for the muscles of the human hand. To address this issue, a presence/absence scoring system was developed for twelve sites of muscle origin and insertion in the metacarpals and phalanges, which was used to determine bilateral asymmetry in the hands of 31 individuals from the Naval Hospital Cemetery site in Greenwich, London. Analysis found observable variation in MSM development between and within the hands, which could be used to determine patterns of asymmetry within the sample. Comparisons with MSM scores from the humeri of these individuals indicate a differentiation in MSM development and asymmetry between these anatomical regions. Levels of asymmetry in the hands and humeri were generally low, with only the dorsal interossei displaying statistically significant asymmetry. Subsequent upper limb MSM research will benefit from the inclusion of data from the hands. These results do not support the continued use of the humerus as a proxy for MSM expression across the upper limb as a whole and suggest that important information regarding behavioural asymmetry in the hands is being lost because of the continual exclusion of this anatomical unit from MSM research
The expression of asymmetry in hand bones from the medieval cemetery at Écija, Spain
No full textThe unique nature of ‘handedness’ in modern humans poses questions about the development of this trait in both extinct hominid species and archaeological populations. An examination of the expression of hand preference in skeletal material is required to answer such questions. The main focus of previous research on asymmetry and hand preference has been on the bones of the upper limb, rather than those of the hand. This study addresses this issue by exploring the expression of asymmetry in the metacarpals and phalanges in 65 adult skeletons from the Medieval Muslim cemetery in Écija, Spain. From comparisons of metric properties of the bones and muscle marker development, varying patterns of asymmetry distribution were found. Sex was found to have a highly significant effect on metric properties, but not on asymmetry scores or muscle development. Age was not found to be significant in any of the analyses. These results suggest that the expression of hand preference varies throughout the hand, and is influenced by the method with which it is assessed. The bones of the hand have an important contribution to make to handedness research, as long as care is paid to associated methodological issue
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Light responses in Photoperiodism in Arabidopsis thaliana
No full textADO1: An Arabidopsis blue light photoreceptor We have reported the characterization of an Arabidopsis gene encoding the ADAGIO 1 (ADO1) protein (Jarillo et al., 2001a). ADO1 contains a LOV domain, similar to WHITE COLLAR 1 (WC1), a photoreceptor for entrainment of Neurospora circadian rhythms (Froehlich et al., 2002), as well as PHOT1 and PHOT2, the blue light photoreceptors for phototropism (Briggs et al., 2001; Christie et al., 1998; Jarillo et al., 2001b; Kinoshita et al., 2001). Loss of function ado1 mutants show an unusually long periodicity for their free running circadian rhythm (Jarillo et al., 2001a). This observation holds for plants grown under white light as well as blue light and surprisingly, plants grown under red light also show altered circadian properties. The similarity of the LOV domain of ADO1 to those of PHOT1, PHOT2 and WC1 (known flavoprotein photoreceptors) as well as the genetic and molecular properties of ADO1, indicate that ADO1 is likely a new class of blue light photoreceptor. Indeed, the LOV domain of the related FKF1/ADO3 has been shown to bind FMN, and exhibit the in vitro photochemistry characteristic of PHOT1 (Imaizumi et al., 2003). Furthermore, ZTL/ADO1 has been shown to participate in the circadian and proteasome mediated degradation of the Arabidopsis clock protein, TOC1 (Mas et al., 2003). We also showed that the ado1 mutation selectively confers hypersensitivity to red light — when grown under red light (but not blue light) the ado1 mutant possesses an unusually short hypocotyl. This red light hypersensivity is even more severe in a triple ado1 ado2 ado3 mutant — ADO2 and ADO3 being the two other members of this ADAGIO gene family. This finding of a mutant phenotype under red light is somewhat unexpected for a protein thought to function as a photoreceptor for blue light. We have pursued our studies of ADO1 by preparing a mutant gene for which we have altered the codon for the cysteine residue conserved in all LOV domains. It is this cysteine residue that forms a covalent adduct with the bound flavin in the photocycle of PHOT1 and FKF1. In the mutant ADO1 this cysteine is replaced by an alanine. We argue that if ADO1 functions as a photoreceptor in a similar fashion to PHOT1, then this mutant ADO1 should not be able to rescue the altered circadian phenotype of ado1 mutant plants. We find under white light, that indeed this is the case. Experiments underway are aimed at determining if the altered circadian phenotype under blue and red light are similarly unable to be rescued by the mutant gene, and we are performing similar experiments under red light with respect to the defect in hypocotyl elongation. The results from these experiments will likely support the hypothesis that ADO1 functions as a blue light photoreceptor, and they will address the question concerning whether or not the altered properties of the ado1 mutant under red light are also a reflection of this photoreceptor function. References. Briggs, W. R., Beck, C. F., Cashmore, A. R., Christie, J. M., Hughes, J., Jarillo, J. A., Kagawa, T., Kanegae, H., Liscum, E., Nagatani, A., et al. (2001). The phototropin family of photoreceptors. Plant Cell 13, 993-997. Christie, J. M., Reymond, P., Powell, G. K., Bernasconi, P., Raibekas, A. A., Liscum, E., and Briggs, W. R. (1998). Arabidopsis NPH1: A flavoprotein with the properties of a photoreceptor for phototropism. Science 282, 1698-1701. Froehlich, A. C., Liu, Y., Loros, J. J., and Dunlap, J. C. (2002). White Collar-1, a circadian blue light photoreceptor, binding to the frequency promoter. Science 297, 815-819. Imaizumi, T., Tran, H. G., Swartz, T. E., Briggs, W. R., and Kay, S. A. (2003). FKF1 is essential for photoperiodic-specific light signalling in Arabidopsis. Nature 426, 302-306. Jarillo, J. A., Capel, J., Tang, R.-H., Yang, H.-Q., Alonso, J. M., Ecker, J. R., and Cashmore, A. R. (2001a). An Arabidopsis circadian clock component interacts with both CRY1 and phyB. Nature 410, 487-490. Jarillo, J. A., Gabrys, H., Capel, J., Alonso, J. M., Ecker, J. R., and Cashmore, A. R. (2001b). Phototropin-related NPL1 controls chloroplast relocation induced by blue light. Nature 410, 952-954. Kinoshita, T., Doi, M., Suetsugu, N., Kagawa, T., Wada, M., and Shimazaki Ki, K. (2001). phot1 and phot2 mediate blue light regulation of stomatal opening. Nature 414, 656-660. Mas, P., Kim, W. Y., Somers, D. E., and Kay, S. A. (2003). Targeted degradation of TOC1 by ZTL modulates circadian function in Arabidopsis thaliana. Nature 426, 567-570
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The expression of bilateral asymmetry in the hands and humeri: a methodological comparison
No full textThe population-level preference for the use of the right hand is one of the defining characteristics of Homo sapiens and as such, its evolutionary origins within the human genus remain a topic of interest. Identifying hand preference in extinct hominin species is complicated by the difficulty in distinguishing markers of laterality in the bones of the upper limb. These difficulties are further compounded by the range of osteological methods available to study asymmetry and the under-representation of the bones of the hand in such studies.To better understand the evolution of handedness within the hominin lineage, the effect of methodology on asymmetry expression must first be clarified, as this in turn influences our notions of handedness in individuals and groups. The current study took an inclusive approach to the measurement of upper limb asymmetry in both modern human and non-human primate samples. To assess the contribution that the bones of the hand can make to asymmetry research, data from the metacarpals and phalanges were compared with that from the humerus, a more commonly-studied region of the upper limb. Both metric and musculoskeletal stress marker (MSM) data were collected and compared in order to assess the comparability of asymmetry profiles generated by contrasting methodological approaches. Asymmetry was determined for a sample of modern human skeletons and a non-human primate sample comprising Pan troglodytes schweinfurthii and Gorilla gorilla gorilla.Two key findings emerge from these analyses: 1) The expression of asymmetry differs, in terms of both direction and magnitude, between the bones of the hand and the humerus. Differences are also apparent between the metacarpals and phalanges. 2) Metric and MSM methods differ in the asymmetry profiles they generate, with the MSM method generally underestimating the magnitude of asymmetry present in a sample, relative to that identified by a metric approach. In addition, the various skeletal samples studied exhibit variation in their relative asymmetry profiles which can be attributed to potential differences in functional recruitment patterns in the upper limbs of these individuals.Together, these findings clearly highlight the care that must be taken in analyses of asymmetry, due to the level of methodological variation present in currently inter-changeable approaches. The relatively neglected region of the hand has an important contribution to make to our understanding of asymmetry in the upper limb. The results of this study recommend the adoption of a more inclusive approach to the study of upper limb bilateral asymmetry, particular when inferences are to be made regarding handedness. By combining methodological approaches and incorporating data from across the upper limb, a more accurate picture of asymmetry expression will emerge and allow us to better understand the evolutionary development of this trait in our hominin ancestors
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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