The influence of preparedness on rapid stepping in young and older adults

Objective: To investigate the influence of age and preparation level on postural muscle activation and step completion time during a rapid step task. Design: Postural muscle onset times (EMG) and ground reaction forces were recorded from healthy young (n = 20, age 21 +/- 3 years) and older (n = 25, age 71 +/- 5 years) female adults during a choice reaction-time stepping paradigm. Main outcome measures: Onset times of six trunk and hip muscles, reaction time and components of the step (weight shift time, step time and task time) were recorded. Results: Muscle activation was delayed and movement time was lengthened in both young and older adults when poorly prepared for a stepping task. While reduced preparation did not influence older adults to a greater extent than young adults, the slowest step response and completion time was evident in older adults when poorly prepared to move. Conclusions: A late postural response when poorly prepared to move may be a contributing factor to an increased risk of overbalancing in older adults. Future assessment of and intervention to improve postural stability in older adults should be expanded to incorporate tasks performed at various levels of preparation.

Optimising high-intensity treadmill training using the running speed at maximal O-2 uptake and the time for which this can be maintained

The aim of this study was to compare the effects of two high-intensity, treadmill interval-training programs on 3000-m and 5000-m running performance. Maximal oxygen uptake ((V) over dot O-2max), the running speed associated with (V) over dot O-2max (nu (V) over dot O-2max), the time for which nu (V) over dot O-2max can be maintained (T-max), running economy (RE), ventilatory threshold (VT) and 3000-m and 5000-m running times were determined in 27 well-trained runners. Subjects were then randomly assigned to three groups; (1) 60% T-max (2) 70% T-max and (3) control. Subjects in the control group continued their normal training and subjects in the two T-max groups undertook a 4-week treadmill interval-training program with the intensity set at nu (V) over dot O-2max and the interval duration at the assigned T-max. These subjects completed two interval-training sessions per week (60% T-max = six intervals/session, 70% T-max group = five intervals/session). Subjects were re-tested on all parameters at the completion of the training program. There was a significant improvement between pre- and post-training values in 3000-m time trial (TT) performance in the 60% T-max group compared to the 70% T,,a, and control groups [mean (SE); 60% T-max = 17.6 (3.5) s, 70% T-max = 6.3 (4.2) s, control = 0.5 (7.7) s]. There was no significant effect of the training program on 5000-m TT performance [60% T-max = 25.8 (13.8) s, 70% T-max = 3.7 (11.6) s, control = 9.9 (13.1) s]. Although there were no significant improvements in (V) over dot O-2max, nu (V) over dot (2max) and RE between groups, changes in (V) over dot O-2max and RE were significantly correlated with the improvement in the 3000-m TT. Furthermore, VT and T-max were significantly higher in the 60% Tmax group post-compared to pre-training. In conclusion, 3000-m running performance can be significantly improved in a group of well-trained runners, using a 4-week treadmill interval training program at nu (V) over dot O-2max with interval durations of 60% T-max.

Clinical supervision in school counselling and career counselling: Is it time to develop a new story?

Supervision provides benefits for school counsellors and career counsellors such as support, an opportunity to gain new ideas and strategies, and personal and professional development. Despite this, studies have also shown that school counsellors perceive that the amount of time they participate in supervision is inadequate. In career counselling, there is little evidence that supervision has even been established as a mainstream professional practice. The reasons for this curious situation, whereby little time is spent on a potentially beneficial activity, are uncertain. The present study investigated the supervisory experiences of a group of school counsellors and career counsellors for a six month period following their completion of an intensive supervision training program. Participants recorded their supervisory experiences in a structured diary. Even though the participants were well informed about supervision, the findings of the present study are consistent with those of previous studies. This history of repeatedly similar findings suggests that it may be timely to ask some fundamental questions about supervision in these two professions. Such questions in turn suggest possible new research directions.

All in Good Time: Exploring Change in Neanderthal Behavioural Complexity

Since their discovery 150 years ago, Neanderthals have been considered incapable of behavioural change and innovation. Traditional synchronic approaches to the study of Neanderthal behaviour have perpetuated this view and shaped our understanding of their lifeways and eventual extinction. In this thesis I implement an innovative diachronic approach to the analysis of Neanderthal faunal extraction, technology and symbolic behaviour as contained in the archaeological record of the critical period between 80,000 and 30,000 years BP. The thesis demonstrates patterns of change in Neanderthal behaviour which are at odds with traditional perspectives and which are consistent with an interpretation of increasing behavioural complexity over time, an idea that has been suggested but never thoroughly explored in Neanderthal archaeology. Demonstrating an increase in behavioural complexity in Neanderthals provides much needed new data with which to fuel the debate over the behavioural capacities of Neanderthals and the first appearance of Modern Human Behaviour in Europe. It supports the notion that Neanderthal populations were active agents of behavioural innovation prior to the arrival of Anatomically Modern Humans in Europe and, ultimately, that they produced an early Upper Palaeolithic cultural assemblage (the Châtelperronian) independent of modern humans. Overall, this thesis provides an initial step towards the development of a quantitative approach to measuring behavioural complexity which provides fresh insights into the cognitive and behavioural capabilities of Neanderthals.

Turbulent Time and Length Scale Measurements in High-Velocity Open Channel Flows

In high-velocity open channel flows, the measurements of air-water flow properties are complicated by the strong interactions between the flow turbulence and the entrained air. In the present study, an advanced signal processing of traditional single- and dual-tip conductivity probe signals is developed to provide further details on the air-water turbulent level, time and length scales. The technique is applied to turbulent open channel flows on a stepped chute conducted in a large-size facility with flow Reynolds numbers ranging from 3.8 E+5 to 7.1 E+5. The air water flow properties presented some basic characteristics that were qualitatively and quantitatively similar to previous skimming flow studies. Some self-similar relationships were observed systematically at both macroscopic and microscopic levels. These included the distributions of void fraction, bubble count rate, interfacial velocity and turbulence level at a macroscopic scale, and the auto- and cross-correlation functions at the microscopic level. New correlation analyses yielded a characterisation of the large eddies advecting the bubbles. Basic results included the integral turbulent length and time scales. The turbulent length scales characterised some measure of the size of large vortical structures advecting air bubbles in the skimming flows, and the data were closely related to the characteristic air-water depth Y90. In the spray region, present results highlighted the existence of an upper spray region for C > 0.95 to 0.97 in which the distributions of droplet chord sizes and integral advection scales presented some marked differences with the rest of the flow.

Time-reversal test for stochastic quantum dynamics

The calculation of quantum dynamics is currently a central issue in theoretical physics, with diverse applications ranging from ultracold atomic Bose-Einstein condensates to condensed matter, biology, and even astrophysics. Here we demonstrate a conceptually simple method of determining the regime of validity of stochastic simulations of unitary quantum dynamics by employing a time-reversal test. We apply this test to a simulation of the evolution of a quantum anharmonic oscillator with up to 6.022×1023 (Avogadro's number) of particles. This system is realizable as a Bose-Einstein condensate in an optical lattice, for which the time-reversal procedure could be implemented experimentally.

Dependence of transient dynamics in a class-C laser upon variation of inversion with time

The transient statistics of a gain-switched coherently pumped class-C laser displays a linear correlation between the first passage time and subsequent peak intensity. Measurements are reported showing a positive or negative sign of this linear correlation, controlled through the switching time and the laser detuning. Further measurements of the small-signal laser gain combined with calculations involving a three-level laser model indicate that this sign fundamentally depends upon the way the laser inversion varies during the gain switching, despite the added dynamics of the laser polarization in the class-C laser. [S1050-2947(97)07112-6].

Do migrants' remittances decline over time? Evidence from Tongans and Western Samoans in Australia

There is concern that Pacific Island economies dependent on remittances of migrants will endure foreign exchange shortages and falling living standards as remittance levels fall because of lower migration rates and the belief that migrants' willingness to remit declines over time. The empirical validity of the remittance-decay hypothesis has never been tested. From survey data on Tongan and Western Samoan migrants in Sydney, this paper estimates remittance functions using multivariate regression analysis. It is found that the remittance-decay hypothesis has no empirical validity, and migrants are motivated by factors other than altruistic family support, including asset accumulation and investment back home.

Experimental control of single-mode laser chaos by using continuous, time-delayed feedback

Control of chaos in the single-mode optically pumped far-infrared (NH3)-N-15 laser is experimentally demonstrated using continuous time-delay control. Both the Lorenz spiral chaos and the detuned period-doubling chaos exhibited by the laser have been controlled. While the laser is in the Lorenz spiral chaos regime the chaos has been controlled both such that the laser output is cw, with corrections of only a fraction of a percent necessary to keep it there, and to period one. The laser has also been controlled while in the period-doubling chaos regime, to both the period-one and -two states.

Dissociation between skin conductance orienting and secondary task reaction time: Time course with a visual discrimination task

A dissociation between two putative measures of resource allocation skin conductance responding, and secondary task reaction time (RT), has been observed during auditory discrimination tasks. Four experiments investigated the time course of the dissociation effect with a visual discrimination task. participants were presented with circles and ellipses and instructed to count the number of longer-than-usual presentations of one shape (task-relevant) and to ignore presentations of the other shape (task-irrelevant). Concurrent with this task, participants made a speeded motor response to an auditory probe. Experiment 1 showed that skin conductance responses were larger during task-relevant stimuli than during task-irrelevant stimuli, whereas RT to probes presented at 150 ms following shape onset was slower during task-irrelevant stimuli. Experiments 2 to 4 found slower RT during task-irrelevant stimuli at probes presented at 300 ms before shape onset until 150 ms following shape onset. At probes presented 3,000 and 4,000 ms following shape onset probe RT was slower during task-relevant stimuli. The similarities between the observed time course and the so-called psychological refractory period (PRF) effect are discussed.

In vivo dynamics of axon pathfinding in the Drosophila CNS: A time-lapse study of an identified motoneuron

We developed a system for time-lapse observation of identified neurons in the central nervous system (CNS) of the Drosophila embryo. Using this system, we characterize the dynamics of filopodia and axon growth of the motorneuron RP2 as it navigates anteriorly through the CNS and then laterally along the intersegmental nerve (ISN) into the periphery. We find that both axonal extension and turning occur primarily through the process of filopodial dilation. In addition, we used the GAL4-UAS system to express the fusion protein Tau-GFP in a subset of neurons, allowing us to correlate RP2's patterns of growth with a subset of axons in its environment. In particular, we show that RP2's sharp lateral turn is coincident with the nascent ISN. (C) 1998 John Wiley & Sons, Inc.

Lepocreadiidae (Digenea) of Australian coastal fishes: new species of Opechona Looss, 1907, Lepotrema Ozaki, 1932 and Bianium Stunkard, 1930 and comments on other species reported for the first time or poorly known in Australian waters

Opechona austrobacillaris n, sp. is described from Pomatomus saltatrix from marine sites off Western Australia and New South Wales, Australia. It differs from O. bacillaris in its elongate outline, small ventral sucker, longer pseudoesophagus (relative to the oesophagus), relatively shorter ventral sucker to ovary distance and the relatively longer post-testicular region. Lepotrema monile n. sp. is described from Pomacentrus wardi from Heron Island, Queensland. It differs from its congeners in the sphincter around the distal metraterm and the more-or-less oval ovary. Bianium spongiosum n. sp, is described from Ostracion cubicus from Lizard Island, Queensland. It differs from its congeners in lacking lateral flaps in the forebody, but in having large, internal spongiform patches in the lateral forebody. The following species are redescribed from Australian sites: Lepocreadium oyabitcha from Abudefduf whitleyi, Lizard Island; Clavogalea trachinoti from Trachinotus botla, Heron Island and T. coppingeri, New South Wales, Stradbroke Island, Queensland and Heron Island; Myzoxenus insolens from Notolabrus parilus, Western Australia; Bulbocirrus aulostomi from Aulostomus chinensis, Heron Island; Lepocreadioides orientalis [new synonyms: Bicaudum interruptum Bilqees, 1973; Lepocreadioides interruptum (Bilqees, 1973) Madhavi, Narasimhulu & Shameem, 1986; Lepocreadioides discum Wang, 1986; Lepocreadioides sp. of Karyakarte & Yadav (1976)] from Cynoglossus bilineata, Moreton Bay, Queensland; Hypocreadium patellare from Sufflamen chrysopterus, Heron Island; Echeneidocoelium indicum from Echeneis naucrates, Heron Island; Multitestis pyriformis from Epinephelus cyanopodus, Heron Island; Pseudopisthogonoporus vitellosus from Naso brevirostris, Heron Island; and Bianium hispidum from Torquigener whitleyi and T. pleurogramma, southern Queensland. Only M. solens and M. pyriformis have been reported from Australian waters before; both are new host records.

Search for time variation of the fine structure constant

An order of magnitude sensitivity gain is described for using quasar spectra to investigate possible time or space variation in the fine structure constant alpha. Applied to a sample of 30 absorption systems, spanning redshifts 0.5 < z < 1.6, we derive limits on variations in alpha over a wide range of epochs. For the whole sample, Delta alpha/alpha = (-1.1 +/- 0.4) x 10(-5). This deviation is dominated by measurements at z > 1, where Delta alpha/alpha = (-1.9 +/- 0.5) x 10(-5). For z < 1, Delta alpha/alpha = (-0.2 +/- 0.4) x 10(-5). While this is consistent with a time-varying alpha, further work is required to explore possible systematic errors in the data, although careful searches have so far revealed none.