Gait termination : a review of experimental methods and the effects of aging and gait pathologies

The study of human gait has expanded and diversified to the extent that it is now possible to identify a substantive literature concerning a variety of gait tasks, such as gait initiation [Halliday SE, Winter DA, Frank JS, Patla AE, Prince F. The initiation of gait in young, elderly, and Parkinson's disease subjects. Gait Posture 1998;8:8–14; Mickelborough J, van der Linden ML, Tallis RC, Ennos AR. Muscle activity during gait initiation in normal elderly people. Gait Posture 2004;19:50–57], stepping over and across obstacles [Patla AE, Prentice SD, Robinson C, Newfold J. Visual control of locomotion: strategies for changing direction and for going over obstacles. J Exp Psych 1991;17:603–34; Chen, HC, Ashton-Miller JA, Alexander NB, Schultz AB. Effect of age and available response time on ability to step over an obstacle. J Gerontol 1994;49:227–33; Sparrow WA, Shinkfield AJ, Chow S, Begg RK. Gait characteristics in stepping over obstacles. Hum Mov Sci 1996;15:605–22; Begg RK, Sparrow WA, Lythgo ND. Time-domain analysis of foot–ground reaction forces in negotiating obstacles. Gait Posture 1998;7:99–109; Patla AE, Rietdyk S. Visual control of limb trajectory over obstacles during locomotion: effect of obstacle height and width. Gait Posture 1993;1:45–60] negotiating raised surfaces such as curbs and stairs [Begg RK, Sparrow WA. Gait characteristics of young and older individuals negotiating a raised surface: implications for the prevention of falls. J Gerontol Med Sci 2000;55A:147–54; Mcfayden BJ, Winter DA. An integrated biomechanical analysis of normal stair ascent and descent. J Biomech 1988;21:733–44]. In addition, increasing research interest in age-related declines in gait that might predispose individuals to falls has engendered a very extensive literature concerning ageing effects on gait. While rapid locomotor adjustments are common in the course of daily activities there has been no previous review of the findings concerning gait adaptations when walking is terminated both rapidly and unexpectedly. The aims of this review were first, to summarise the key research findings and methodological considerations from studies of termination. The second aim was to demonstrate the effects of ageing and gait pathologies on termination with respect to the regulation of step characteristics, lower-limb muscle activation patterns and foot–ground reaction forces.

Thermoenergetics of pre-moulting and moulting kookaburras (Dacelo novaeguineae): they're laughing.

We examined the effect of temperature on resting metabolic rate in seven field-captured laughing kookaburras (Dacelo novaeguineae) during late winter and early spring. Basal metabolic rate averaged 201±3.4 ml O₂ h^–1 (0.603 ml O₂ g^–1 h^–1). Overall thermal conductance (K_o) declined with ambient temperature (T_a) and averaged 0.026 ml O₂ g^–1 h^–1 °C^–1 at T_as<10 °C. Day-night differences in body temperatures (2.6 °C) and in alpha-phase versus rho-phase minimum metabolic rates were much greater (33%) than predicted for 340-g nonpasserine birds and suggest that these animals operate as low-metabolic intensity animals in their rest phase, but normal-metabolic intensity animals during their active phase. Metabolic rate was measured in four of the same birds undergoing moult. Thermal conductance increased to 60% above pre-moult values about 6 weeks after moult began. Basal metabolic rate of moulting birds showing peak thermal conductance readings averaged 17 ml O₂ h^–1 higher than pre-moult measurements. Although this increase was not statistically significant, we believe the moult costs of kookaburras are too low to overcome the inherent variability of BMR determination. We suggest that moult costs of kookaburras are only somewhat higher than the measured costs of protein synthesis of other endotherms.

Body dissatisfaction and body change strategies among adolescents : a longitudinal investigation

This thesis examined body dissatisfaction and body change behaviors among adolescent girls and boys from a biopsychosocial framework. The contribution of biological, psychological and sociocultural factors were examined in relation to body dissatisfaction, weight loss, weight gain and increased muscle tone behaviors among early adolescent girls and boys. In particular, pubertal maturation, body mass index (BMI), perception of body shape and size and psychological factors, such as depression, anxiety, ineffectiveness, self-esteem and perfectionism, were examined as possible factors that may precipitate or maintain body dissatisfaction and engagement in body change strategies. The sociocultural factors evaluated were the quality of family and peer relationships, as well as the influence of family and peers in predicting the adoption of specific body change strategies. The specific mechanisms by which these influences were transmitted were also examined. These included perceived discussion, encouragement and modelling of various body change strategies, as well as perceived teasing about body shape and size. A number of separate cross-sectional and longitudinal studies were conducted to examine the above relationships and identify the factors that contribute to weight loss, weight gain and increased muscle tone behaviors in adolescents. Study 1 examined the psychometric properties and principal components structure of the Bulimia Test Revised (BULIT-R; Thelen, Farmer, Wonderlich, & Smith, 1991) to assess its applicability to adolescent samples. Study 2 investigated the nature of body dissatisfaction and weight loss behaviors among 603 adolescents (306 girls and 297 boys) using a standardised questionnaire. This preliminary study was conducted to ascertain whether variables previously found to be relevant to adolescent girls, could also be related to the development of body dissatisfaction and weight loss behaviors among adolescent boys. Studies 3 and 4 described the development and validation of a body modification scale that measured weight loss, weight gain and increased muscle tone behaviors. Studies 5 and 6 were designed to modify an Excessive Exercise Scale developed by Long, Smith, Midgley, and Cassidy (1993) into a shorter form, and validate this scale with an adolescent sample. Study 7 investigated the factors that contribute to weight loss, weight gain and increased muscle among adolescent girls and boys both cross-sectionally and longitudinally (over one year). Structural equation modelling was used to examine associations among self-reported body dissatisfaction, body change strategies and a range of biological, psychological and sociocultural variables both cross-sectionally and longitudinally. Overall, the results suggested that both girls and boys experience body dissatisfaction and engage in a number of different body change strategies in order to achieve an ideal size. A number of gender similarities and differences were identified in the expression of body dissatisfaction and the adoption of body change strategies for both girls and boys. Girls were more likely than boys to report body dissatisfaction and engage in weight loss behaviors, while boys were more likely than girls to engage in weight gain and increased muscle tone behaviors. Generally, the same factors were found to contribute to weight loss, and more specifically, bulimic symptomatology, ad weight gain in both adolescent girls and boys. While a combination of biological, psychological and sociocultural factors contributed to bulimic symptomatology, only biological and psychological factors were found to contribute to weight gain in adolescents. The most notable gender differences were found in the model of increased muscle tone. Sociocultural and biological factors contributed to increased muscle tone behaviors in girls, while sociocultural and psychological factors were implicated in these behaviors in adolescent boys. With the exception of the model of increased muscle tone for boys, body dissatisfaction was a consistent factor in the adoption of body change behaviors. Consistent with previous investigations, the present thesis provides empirical support for the need to examine the etiology and maintenance of such concerns and behaviors from a multifaceted perspective.

Better access to mental health program : influence of mental health occupational therapy

Background/aim

The Better Access to Mental Health program has enabled eligible occupational therapists to provide services to people with a mental health condition. No studies have yet reported the influence of occupational therapy under this scheme. The aim of this study was to investigate whether attending an occupational therapist under this initiative influences change in psychological distress of clients as measured by the Kessler Psychological Distress Scale (K10).
Method

A quasi-experimental pretest–posttest design, using pre-existing data collected in the process of regular treatment was used. Data from a total of 31 clients (mean = 17.13 years, SD = 3.603) were accessed for this study. Pre- and post-intervention scores on the K10 were used to determine if psychological distress had changed over the course of intervention.
Results

Highly significant improvements (P < 0.001) were found between the K10 pre-intervention score (mean = 25.68, SD = 9.944) and the K10 post-intervention score (mean = 21.00, SD = 9.212). Male K10 post-intervention scores (mean = 17.64, SD = 5.3) significantly improved (P = 0.05), whereas results for females were not statistically significant. Medication use, diagnosis, age, number of sessions and prior contact with health services did not influence the results. Results from specific evidence-based interventions were not able to be considered in this study.
Conclusion

The results of this study demonstrate effectiveness of occupational therapy services for adolescents and provide support for the ongoing participation of occupational therapists in this scheme.

On the determination of the number of factors using information criteria with data-driven penalty

As is well known, when using an information criterion to select the number of common factors in factor models the appropriate penalty is generally indetermine in the sense that it can be scaled by an arbitrary constant, c say, without affecting consistency. In an influential paper, Hallin and Liška (J Am Stat Assoc102:603–617, 2007) proposes a data-driven procedure for selecting the appropriate value of c. However, by removing one source of indeterminacy, the new procedure simultaneously creates several new ones, which make for rather complicated implementation, a problem that has been largely overlooked in the literature. By providing an extensive analysis using both simulated and real data, the current paper fills this gap.