Identification of Movement Strategies during the Sit-to-Walk Movement in Patients with Knee Osteoarthritis

Patients with osteoarthritis (OA) of the knee commonly alter their movement to compensate for deficiencies. This study presents a new numerical procedure for classifying sit-to-walk (STW) movement strategies. Ten control and twelve OA participants performed the STW task in a motion capture laboratory. A full body biomechanical model was used. Participants were instructed to sit in a comfortable self-selected position on a stool height adjusted to 100% of their knee height and then stand and pick up an object from a table in front of them. Three matrices were constructed defining the progression of the torso, feet and hands in the sagittal plane along with a fourth expressing the location of the hands relative to the knees. Hierarchical clustering (HC) was used to identify different strategies. Trials were also classified as to whether the left (L) and right (R) extremities used a matching strategy (bilateral) or not (asymmetrical). Fisher’s exact test was used to compare this between groups. Clustering of the torso matrix dichotomised the trials in two major clusters; subjects leaning forward (LF) or not. The feet and hands matrices revealed sliding the foot backward (FB) and moving an arm forward (AF) strategies respectively. Trials not belonging in the AF cluster were submitted to the last HC of the fourth matrix exposing three additional strategies, the arm pushing through chair (PC), arm pushing through knee (PK) and arm not used (NA). The control participants used the LF+FBR+PK combination most frequently whereas the OA participants used the AFR+PCL. OA patients used significantly more asymmetrical arm strategies, p=0.034. The results demonstrated that control and OA participants favour different STW strategies. The OA patients asymmetrical arm behaviour possibly indicates compensating for weakness of the affected leg. These strategy definitions may be useful to assess post-operative outcomes and rehabilitation progress

Deformed Minkowski spaces: clasification and properties

Using general but simple covariance arguments, we classify the `quantum' Minkowski spaces for dimensionless deformation parameters. This requires a previous analysis of the associated Lorentz groups, which reproduces a previous classification by Woronowicz and Zakrzewski. As a consequence of the unified analysis presented, we give the commutation properties, the deformed (and central) length element and the metric tensor for the different spacetime algebras.Comment: Some comments/misprints have been added/corrected, to appear in Journal of Physics A (1996

In vitro polishing effectiveness of interdental aids on root surfaces

. The purpose of this study was: (1) to determine whether polishing standardized proximal root surfaces with dental floss, Superfloss, wood and plastic interdental cleaners, using a polishing paste, produces any significant change on root surface roughness; and (2) to determine the effectiveness of different number of strokes in polishing. 80 tooth specimens were prepared, 10 in each of 8 sample groups. Each proximal root surface was standardized with 600A grit silicone carbide paper and polished with either waxed dental floss, Superfloss, wood or plastic interdental cleaners, using alkali aluminum silicate polishing paste. All specimens were mounted on a flossing machine and polished with 10 or 20 strokes. Before and after polishing, measurements were recorded with the Surfanalyzer 150 System to produce profile and average roughness tracings. Average maximum peak heights, mean number of peaks, and mean average roughness values were calculated from the tracings. The data were analyzed statistically by paired t-test and Student t-test. No significant mean differences were found between the number of strokes used. No significant differences were found for waxed dental floss in relation to the values analyzed. Significant differences were found for maximum peak heights for Superfloss following 20 strokes of polishing. However, no significant differences were found for Superfloss for mean number of peaks and average roughness. Significant differences were found for average roughness values, maximum peak heights, and mean number of peaks for the wood and plastic interdental cleaners. It was concluded that root surface roughness increased significantly with the use of wood and plastic interdental cleaners but not with waxed dental floss or Superfloss.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75532/1/j.1600-051X.1986.tb00853.x.pd

Applying a values-based decision process to facilitate co-management of threatened species in Aotearoa New Zealand

Ko koe ki tēnā, ko ahau ki tēnai kīwai o te kete (you at that, and I at this handle of the basket). This Māori (New Zealanders of indigenous descent) saying conveys the principle of cooperation—we achieve more through working together, rather than separately. Despite decades of calls to rectify cultural imbalance in conservation, threatened species management still relies overwhelmingly on ideas from Western science and on top-down implementation. Values-based approaches to decision making can be used to integrate indigenous peoples’ values into species conservation in a more meaningful way. We used such a values-based method, structured decision making, to develop comanagement of pekapeka (Mystacina tuberculata) (short-tailed bat) and tara iti (Sternula nereis davisae) (Fairy Tern) between Māori and Pākehā (New Zealanders of European descent). We implemented this framework in a series of workshops in which facilitated discussions were used to gather expert knowledge to predict outcomes and make management recommendations. For both species, stakeholders clearly stated their values as fundamental objectives from the start, which allowed alternative strategies to be devised that naturally addressed their diverse values, including mātauranga Māori (Māori knowledge and perspectives). On this shared basis, all partners willingly engaged in the process, and decisions were largely agreed to by all. Most expectations of conflicts between values of Western science and Māori culture were unfounded. Where required, positive compromises were made by jointly developing alternative strategies. The values-based process successfully taha wairua taha tangata (brought both worlds together to achieve the objective) through codeveloped recovery strategies. This approach challenges the traditional model of scientists first preparing management plans focused on biological objectives, then consulting indigenous groups for approval. We recommend values-based approaches, such as structured decision making, as powerful methods for development of comanagement conservation plans between different peoples

Consumption caught in the cash nexus.

During the last thirty years, ‘consumption’ has become a major topic in the study of contemporary culture within anthropology, psychology and sociology. For many authors it has become central to understanding the nature of material culture in the modern world but this paper argues that the concept is, in British writing at least, too concerned with its economic origins in the selling and buying of consumer goods or commodities. It is argued that to understand material culture as determined through the monetary exchange for things - the cash nexus - leads to an inadequate sociological understanding of the social relations with objects. The work of Jean Baudrillard is used both to critique the concept of consumption as it leads to a focus on advertising, choice, money and shopping and to point to a more sociologically adequate approach to material culture that explores objects in a system of models and series, ‘atmosphere’, functionality, biography, interaction and mediation

Negative Experiences in Television Programming : A View from the Other Side

Many professional archaeologists will engage with television. There seems to be little guidance- other than trial and error and personal communications - for navigating interactions with media production companies. Here, through a series of informal questions and answers, I present some issues with which one might be confronted in such engagements. I base my discussions on personal experience, literature, and conversations with experienced colleagues. A key point is that media production companies' agendas and priorities often differ from those of archaeologists. While the article draws on experiences from Europe and North America, it has relevance for archaeologists working with television everywhere.Peer reviewe

Hierarchical Control Implementation for Meshed AC/Multi-terminal DC Grids with Offshore Windfarms Integration

Although the integration of meshed multi-terminal direct current (MTDC) grids with the existing AC grid has some added economic advantages, significant challenges are encountered in such systems. One of the major challenges is ensuring secure and optimal operation of the combined AC/MTDC grid considering the stability requirements of AC and DC grids at different operating conditions. This paper presents the implementation of hierarchical control for the combined AC/MTDC grid. The hierarchical control is based on the well-established three-layered control of the AC power system, comprising primary, secondary, and tertiary controls. A set of appropriate control methods are proposed for the primary, secondary, and tertiary control layers to accomplish the identified requirements for secure and optimal operation of the combined AC/MTDC grid

Atomic-scale insights into the tribochemical wear of diamond on quartz surfaces

A detailed understanding of diamond wear is crucial due to its use in high-performance cutting tools. Despite being a much harder material, diamond shows appreciable wear when cutting silicon dioxides due to a tribochemical mechanism. Here, we use nonequilibrium molecular dynamics simulations with a reactive force field to investigate the wear of single-crystal diamond tips sliding on α-quartz surfaces. Atom-by-atom attrition of carbon atoms is initiated by the formation of C-O interfacial bonds, followed by C-C cleavage, and either diffusion into the substrate or further oxidation to form CO2 molecules. Water molecules dissociate to form hydroxyl groups, which passivates the surfaces and reduces interfacial bonding and wear. At low loads, the initial wear rate increases exponentially with temperature and normal stress, consistent with stress-augmented thermally activated wear models. At higher loads, the initial wear rate becomes less sensitive to the normal stress, eventually plateauing towards a constant value. This behaviour can be described using the multibond wear model. After long sliding distances, wear also occurs through cluster detachment via tail fracture. Here, wear becomes approximately proportional to the sliding distance and normal load, consistent with the Archard model. The normalised wear rates from the simulations are within the experimentally-measured range

A Study of Cosmic Ray Composition in the Knee Region using Multiple Muon Events in the Soudan 2 Detector

Deep underground muon events recorded by the Soudan 2 detector, located at a depth of 2100 meters of water equivalent, have been used to infer the nuclear composition of cosmic rays in the "knee" region of the cosmic ray energy spectrum. The observed muon multiplicity distribution favors a composition model with a substantial proton content in the energy region 800,000 - 13,000,000 GeV/nucleus.Comment: 38 pages including 11 figures, Latex, submitted to Physical Review