Comparing the attractor strength of intra- and interpersonal interlimb coordination using cross-recurrence analysis

Previous research has demonstrated that intra- and interpersonal rhythmic interlimb coordination are both constrained by the self-organizing entrainment process of coupled oscillators. Despite intra- and interpersonal coordination exhibiting the same stable macroscopic movement patterns the variability of the coordination is typically found to be much greater for inter- compared to intrapersonal coordination. Researchers have assumed that this is due to the interpersonal visual-motor coupling producing a weaker attractor dynamic than the intrapersonal neuromuscular coupling. To determine whether this assumption is true, two experiments were conducted in which pairs of participants coordinated hand-held pendulums swung about the wrist, either intra- and interpersonally. Using the cross-recurrence statistics of percent recurrence and maxline to independently index the level of noise and the attractor strength of the coordination, respectively, the results confirmed that the attractor strength was significantly weaker for inter- compared to intrapersonal coordination and that a similar magnitude of noise underlies both.

Period basin of entrainment for unintentional visual coordination

Researchers have demonstrated that a person's rhythmic movements can become unintentionally entrained to another person's rhythmic movements or an environmental event. There are indications, however, that in both cases the likelihood of entrainment depends on the difference between the uncoupled periods of the two rhythms. The authors examined the range of period differences over which unintentional visual coordination might occur in 16 participants (Experiment 1) and 15 participants (Experiment 2). Cross-spectral coherence analysis and the distribution of continuous relative phase revealed that visual entrainment decreased as the difference between participants' preferred period and the experimenter-determined period of the environmental stimulus increased. The present findings extend the dynamical systems perspective on person-environment coupling and highlight the significance of period difference to the emergence of unintentional coordination.

Functionalised hybrid materials of conducting polymers with individual wool fibers

Composites of natural protein materials, such as merino wool, with the conducting polymers polypyrrole (PPy) and polyaniline (PAn) have been successfully synthesised. In doing so, hybrid materials have been produced in which the mechanical strength and flexibility of the fibers is retained whilst also incorporating the desired chemical and electrical properties of the polymer. Scanning electron microscopy shows PPy coatings to comprise individual polymer spheres, approximately 100 to 150 nm in diameter. The average size of the polymer spheres of PAn was observed to be approximately 50 to 100 nm in diameter. These spheres fuse together in a continuous sheet to coat the fibers in their entirety. The reduction of silver ions to silver metal nanoparticles onto the redox active polymer surface has also been successful and thus imparts anti-microbial properties to the hybrid materials. This gives rise to further applications requiring the inhibition of microbial growth. The chemical and physical characterisation of such products has been undertaken through scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), electrical conductivity, cyclic voltammetry, X-ray photoelectron spectroscopy (XPS) and the testing of their anti-microbial activity.

Immobilisation of fully sulfonated polyaniline on nanostructured calcium silicate

Up to 7.4% (w/w) of the sulfonated polyaniline, poly(2-methoxyaniline-5-sulfonic acid) (PMAS) can be absorbed onto nanostructured calcium silicates. Spectroscopic and leaching studies on the novel PMAS-silicate nanocomposites obtained indicate that attachment of the PMAS occurs via electrostatic binding of PMAS sulfonate groups to Ca2+ sites on the silicates. The surface area and pore volume of the nanocomposites are comparable to those of pure silicate and increase the surface area of the PMAS polymer by several orders of magnitude. The PMAS emeraldine salt in the nanocomposites retains its chemical reactivity, being readily oxidised and reduced to its pernigraniline and leucoemeraldine forms, respectively. The conductivity of the composite is comparable to that of the pure PMAS, several orders of magnitude higher than that of dried nanostructured calcium silicate.

Stress and anger as contextual factors and preexisting cognitive schemas: predicting parental child maltreatment risk

Progress in the child maltreatment field depends on refinements in leading models. This study examines aspects of social information processing theory (Milner, 2000) in predicting physical maltreatment risk in a community sample. Consistent with this theory, selected preexisting schema (external locus-of-control orientation, inappropriate developmental expectations, low empathic perspective-taking ability, and low perceived attachment relationship to child) were expected to predict child abuse risk beyond contextual factors (parenting stress and anger expression). Based on 115 parents' self-report, results from this study support cognitive factors that predict abuse risk (with locus of control, perceived attachment, or empathy predicting different abuse risk measures, but not developmental expectations), although the broad contextual factors involving negative affectivity and stress were consistent predictors across abuse risk markers. Findings are discussed with regard to implications for future model evaluations, with indications the model may apply to other forms of maltreatment, such as psychological maltreatment or neglect.

Visual tracking and entrainment to an environmental rhythm

This study investigated the role that visual tracking plays in coupling rhythmic limb movements to an environmental rhythm. Two experiments were conducted in which participants swung a hand-held pendulum while tracking an oscillating stimulus or while keeping their eyes fixed on a stationary location directly above an oscillating stimulus. It was expected that the participants' rhythmic movements would become entrained to the oscillating stimulus in both conditions but that visual tracking would strengthen this entrainment. Experiment 1 investigated the role of visual tracking in establishing unintentional entrainment. Experiment 2 investigated the role of visual tracking in intentional entrainment. As predicted, participants exhibited greater unintentional coordination and more stable intentional coordination when they tracked the stimulus. These findings highlight the importance of understanding the role of eye movements in environmental coordination.

Judging and actualizing intrapersonal and interpersonal affordances

The current study investigated the perception of intrapersonal, interpersonal, and tool-based grasping possibilities. In Experiment 1, participants judged whether they would grasp planks of wood-presented in ascending, descending, and random orders of length-using one hand (1H), two hands (2H), or with a tool that extended their reach (TH). In Experiment 2, participants physically grasped the planks using 1H, 2H, or TH. In Experiments 3 and 4, the choice of TH was replaced with a choice of grasping the planks with another person (2P). The results showed that presentation order influenced the participants' behavior differently in the judgment and action experiments. The same behavioral patterns, however, were observed when participants switched between 1H and 2H, 2H and TH, and 2H and 2P grasping. The point at which participants judged they would switch between the different modes of grasping, as well as the point at which participants physically switched between the grasping modes, occurred at similar action-scaled ratios. The equivalence of perceiving intrapersonal and interpersonal affordances is discussed.

Rocking together: dynamics of intentional and unintentional interpersonal coordination

The current study investigated the interpersonal coordination that occurred between two people when sitting side-by-side in rocking chairs. In two experiments participant pairs rocked in chairs that had the same or different natural periods. By instructing pairs to coordinate their movements inphase or antiphase, Experiment 1 investigated whether the stable patterns of intentional interpersonal coordination were consistent with the dynamics of within person interlimb coordination. By instructing the participants to rock at their own preferred tempo, Experiment 2 investigated whether the rocking chair movements of visually coupled individuals would become unintentionally coordinated. The degree to which the participants fixated on the movements of their co-actor was also manipulated to examine whether visual focus modulates the strength of interpersonal coordination. As expected, the patterns of coordination observed in both experiments demonstrated that the intentional and unintentional interpersonal coordination of rocking chair movements is constrained by the self-organizing dynamics of a coupled oscillator system. The results of the visual focus manipulations indicate that the stability of a visual interpersonal coupling is mediated by attention and the degree to which an individual is able to detect information about a co-actor's movements.

Distinguishing the noise and attractor strength of coordinated limb movements using recurrence analysis

The variability of coupled rhythmic limb movements is assumed to be a consequence of the strength of a movement's attractor dynamic and a constant stochastic noise process that continuously perturbs the movement system away from this dynamic. Recently, it has been suggested that the nonlinear technique of recurrence analysis can be used to index the effects of noise and attractor strength on movement variability. To test this, three experiments were conducted in which the attractor strength of bimanual wrist-pendulum movements (using coordination mode, movement frequency and detuning), as well as the magnitude of stochastic perturbations affecting the variability of these movements (using a temporally fluctuating visual metronome) was manipulated. The results of these experiments demonstrate that recurrence analysis can index parametric changes in the attractor strength of coupled rhythmic limb movements and the magnitude of metronome induced stochastic perturbations independently. The results of Experiments 1 and 2 also support the claim that differences between the variability of inphase and antiphase coordination, and between slow and fast movement frequencies are due to differences in attractor strength. In contrast to the standard assumption that the noise that characterizes interlimb coordination remains constant for different magnitudes of detuning (Delta omega) the results of Experiment 3 suggest that the magnitude of noise increases with increases in |Delta omega|.

Articulatory constraints on interpersonal postural coordination

Cooperative conversation has been shown to foster interpersonal postural coordination. The authors investigated whether such coordination is mediated by the influence of articulation on postural sway. In Experiment 1, talkers produced words in synchrony or in alternation, as the authors varied speaking rate and word similarity. Greater shared postural activity was found for the faster speaking rate. In Experiment 2, the authors demonstrated that shared postural activity also increases when individuals speak the same words or speak words that have similar stress patterns. However, this increase in shared postural activity is present only when participants' data are compared with those of their partner, who was present during the task, but not when compared with the data of a member of a different pair speaking the same word sequences as those of the original partner. The authors' findings suggest that interpersonal postural coordination observed during conversation is mediated by convergent speaking patterns.

Coordination of sucking, swallowing, and breathing and oxygen saturation during early infant breast-feeding and bottle-feeding

This prospective study compared the coordination of sucking, swallowing, and breathing and its relationship to oxygen saturation in infants during breast-feeding and bottle-feeding. After 4 to 6 wk of exclusive breast-feeding, infants began bottle-feedings of expressed human milk using one of two systems: a soft-walled bottle and nipple (system 1, Playtex) or a hard-walled bottle and nipple (system 2, Avent). Infants' sucking, swallowing, breathing, and oxygenation were measured during breast-feeding and bottle-feeding, and coordination of these activities during breast-feeding and bottle-feeding were compared. During breast-feeding, swallowing occurred nonrandomly between breaths and did not interfere with breathing. The same distribution of swallowing occurred in infants fed with system 1, while swallowing occurred randomly in infants fed with system 2. Swallowing significantly increased during bottle-feeding among infants using system 2, but decreased among infants using system 1. Infants using system 2 also had a greater instability in the coordination of sucking, swallowing, and breathing and more perturbation of breathing. Oxygen saturation was significantly higher in infants fed with system 1 compared with system 2. These results suggest that the overall feeding pattern and oxygenation of system 1 are closer to the physiologic norm than system 2.

Hydrothermal oxidation of waste lipids, protein, and starch from New Zealand meat- and vegetable-processing plants

Disposal of organic waste materials from the meat- and vegetable-processing industries historically has been undertaken by dumping, drying followed by combustion, or biological oxidation. As a result of higher intensity processing rates and increasingly stringent legislation, these are no longer economical. Hydrothermal oxidation, also referred to as "wet" oxidation, has been used to lower the chemical and biological oxygen demand of waste samples from the above two industries. The starch-based wastes were readily oxidized without a catalyst. For the lipid and protein-based wastes, the use of copper calcium silicate and nitrate catalysts provided a significant reduction in oxygen demand at 230 degrees C.

The occurrence and distribution of Piptocephalis, syncephalis and Chaetocladium species on dung

Records of the Piptocephalidaceae and Chaetocladiaceae from over 800 samples of dung collected worldwide are analysed. Piptocephalis species were frequent, occurring especially on dung of rabbit (31% of all samples) in temperate regions. Chaetocladium and Syncephalis species were much less frequent. The status of these fungi as coprophils and reasons for the differences in distribution and substrate preference are discussed.

Effects of visual and verbal interaction on unintentional interpersonal coordination

Previous research has demonstrated that people's movements can become unintentionally coordinated during interpersonal interaction. The current study sought to uncover the degree to which visual and verbal (conversation) interaction constrains and organizes the rhythmic limb movements of coactors. Two experiments were conducted in which pairs of participants completed an interpersonal puzzle task while swinging handheld pendulums with instructions that minimized intentional coordination but facilitated either visual or verbal interaction. Cross-spectral analysis revealed a higher degree of coordination for conditions in which the pairs were visually coupled. In contrast, verbal interaction alone was not found to provide a sufficient medium for unintentional coordination to occur, nor did it enhance the unintentional coordination that emerged during visual interaction. The results raise questions concerning differences between visual and verbal informational linkages during interaction and how these differences may affect interpersonal movement production and its coordination.

Boundary effects in reaction-diffusion processes

The effects of a boundary on reaction systems are examined in the framework of the general single-species reaction/coalescence process. The boundary naturally represents the reactants' container, but is applicable to exciton dynamics in a doped TMMC crystal. We show that a density excess, which extends into the system diffusively from the boundary, is formed in two dimensions and below. This implies a surprising result for the magnetization near a fixed spin in the coarsening of the one-dimensional critical Ising model. The universal, dimensionally dependent functional forms of this density excess are given by an exact solution and the field-theoretic renormalization group.

Giant cell tumor of bone

Giant cell tumor of bone is an unusual neoplasm and treatment commonly leads to local recurrence. This can be related to the aggressiveness of the tumor or to the incompleteness of its removal. This study includes 27 cases that presented to our institution between the 1984 and 1994. One case was as a consultation only and 9 cases, either Campanacci Grade 3 or patients with considerable joint destruction, were treated by resection and reconstruction. One case was treated by curettage and cementation. Sixteen cases were treated with a combination of radical curettage, high speed burring, pulsatile lavage, and bone graft (either autograft or allograft mixed with autograft). No other adjuvant therapy was used. All of these 16 cases had a minimum follow-up of 5 years and none had a local recurrence. This study demonstrates that local control of giant cell tumors can be obtained by appropriate staging, resection of aggressive tumors, and by conservative management of the others. Such conservative management provides a bony matrix for the subchondral bone that is preferable to other treatments that have become popular in recent years, including cementation. This should provide better joint function in the longer term. High local recurrence rates have been reported in other series, but by a combination of appropriate selection of cases and by careful treatment of the Campanacci Grade 1 and 2 cases, these patients can have an uncomplicated outcome.

Effects of narcotic and non-narcotic continuous epidural anesthesia on intrapartum fetal heart rate tracings as measured by computer analysis

OBJECTIVE

To evaluate the effect of narcotic and non-narcotic continuous epidural anesthesia on intrapartum fetal heart rate (FHR) tracings as measured by computer analysis.

METHODS

We studied 37 women with uncomplicated pregnancies at term with reactive FHR tracings. The women were randomized to receive epidural anesthesia with either bupivicaine with fentanyl or bupivicaine alone. One-hour FHR tracings were obtained before epidural anesthesia. Thirty minutes after the initial bolus of the epidural a repeat computer analysis of 60-minute FHR tracing was obtained. Median values are reported for FHR parameters with statistical analysis performed by the Mann-Whitney U and Wilcoxon signed rank tests where appropriate. A power calculation was performed using a power of 90% to determine a required sample size of 28 patients. Statistical significance was set at P < .05.

RESULTS

In early first stage of labor, there was no significant difference in pre- and postepidural anesthesia FHR baseline, accelerations of 10 and 15 beats per minute, episodes of high and low variation, and short- and long-term variation when using either narcotic or non-narcotic anesthetic agents.

CONCLUSIONS

Thus, the clinician can consider the use of narcotic as well as non-narcotic continuous epidural anesthesia in the dosages used in our study with its attendant advantages without fear of obscuring the fetal heart rate tracing.

Factors influencing the production of turbidity by goldfish (Carassius auratus)

Experiments were conducted to determine the effect of body size, population size and structure, and temperature upon the level of turbidity generation by goldfish foraging in laboratory pools. Water temperature correlated with turbidity generation, which peaked at 25 °C but declined at 30 °C. Goldfish exhibited diurnal activity at all temperatures except 25 °C, where nocturnal behaviour predominated. Both body length and population size positively influenced turbidity production. Groups of a few large fish produced significantly more turbidity than groups of many small fish of equal biomass. Biomass was therefore a poor predictor of the level of turbidity, making it difficult to predict the impact of goldfish upon multispecific pond communities following successful colonization.

New materials for dielectric simulation of tissues

Two novel materials have been developed to simulate the dielectric properties of human muscle and fat at 1000 MHz. These materials, which are based on ethanediol set with gelatine, are easily made and have good mechanical properties. The complex permittivity, epsilon *, of each material was measured with an open-ended coaxial sensor in conjunction with an automatic network analyser. Values of epsilon * at 1000 MHz and room temperature (49.4-24.4j for the muscle-equivalent material, 8.2-3.6j for the fat-equivalent) compared well with literature values for tissue at body temperature. Thermal properties were also considered. Specific heat capacities of the materials at room temperature were measured by differential scanning calorimetry and found to be very close to values predicted by theory. Densities were also measured and the thermal conductivities estimated. For comparison, new measurements were made of the specific heat and density of human muscle and fat at body temperature.

Determination of sulfur dioxide in grapes: comparison of the Monier-Williams method and two ion exclusion chromatographic methods

Results for determination of sulfur dioxide in grapes were compared by 3 methods: the modified Monier-Williams method, acid distillation/ion exclusion chromatography with electrochemical detection (AD/IEC-EC), and alkali extraction/ion exclusion chromatography with electrochemical detection (AE/IEC-EC). An unusual positive response was observed during the later stage of the Monier-Williams distillation of both control grapes and sulfited grapes. Development of volatile acidic compounds in parallel with this Monier-Williams response and darkening of sample was also observed by collection in an alkali trap and analysis using anion exclusion chromatography and photodiode array detection. No parallel increase in sulfite was observed by the more selective AD/IEC-EC method, which clearly demonstrated that the response observed during the later stage of the Monier-Williams method is a false positive, probably due to caramelization reaction products. Monier-Williams results for grapes containing ca 10 ppm sulfite were in reasonably good agreement with those by either the AD/IEC-EC or AE/IEC-EC methods, presumably because the false positive response in the Monier-Williams analysis compensated for the somewhat incomplete recovery of sulfite. The AE/IEC-EC method is recommended because it is rapid, sensitive, straightforward, and free from interference. Accurate results by Monier-Williams analysis could be obtained by limiting distillation to 60 min and correcting for recovery.

Self-concepts of Costa Rican elementary school children

The Martinek-Zaichkowsky Self-concept Scale was administered to 797 Costa Rican children in Grades 1 to 6. A three-way analysis of variance and Scheffé tests, used in conjunction with a 7 x 6 x 2 factorial design, showed significant differences between school types based on enrollment, grades, and sex. The highest self-concepts were found in the first grade and girls. Children in schools with enrollments under 50 scored significantly lower than those in larger schools. Findings were discussed in relation to literature for children in the USA.

The detection of post-gastrectomy deficiency syndromes in general practice

Post-gastrectomy deficiency syndromes were investigated in a rural practice. The main finding was a high prevalence of iron deficiency both with and without anaemia. Regular checks on iron level in the follow-up of these patients is suggested.

Exceptionally Strong Near-Bottom Flows on the Continental Rise of Nova Scotia

Recent current velocity measurements across the lower continental rise of Nova Scotia show a deep equatorwardflow with speeds (maximum, 73 centimeters per second) among the highest recorded for the deep sea. Silicate measurements indicate that this flow usually consists of southern-source (Antarctic) bottom water. These measurements confirm the existence of a second and deeper western boundary flow that was earlier inferredfrom geological observations.