Parents' perception of the quality of life of preschool children at risk or having developmental disabilities.

Despite increased concern for the health related quality of life (HRQOL) of people with disabilities, little is known about the HRQOL of children with developmental disabilities. The present study aimed to explore the HRQOL of children who were at risk or having developmental disabilities in Hong Kong. Using the parent-reported Chinese Pediatric Quality of Life Inventory (PedsQL), the HRQOL of 173 children (2–4 years) with signs of delays in development was contrasted with that of 132 children with typical development. We found that those who exhibited high risk of developing a developmental disability had significantly lower overall well-being (76.3 ± 13.7 vs. 84.2 ± 11.3; p<0.001) and psychosocial health (71.3 ± 15.6 vs. 82.5 ± 12.9; p<0.001) but not necessarily physical health. The findings are consistent with previous findings in children with different disabilities and chronic illnesses. They suggest children at risk or having DDs need help in restoring their quality of life up to the standard experienced by their healthy peers, particular in psychosocial aspects such as social functioning, emotion functioning, and school functioning.

Internal representation of movement in children with developmental coordination disorder : a mental rotation task

Recent studies show that children with developmental coordination disorder (DCD) have difficulties in generating an accurate visuospatial representation of an intended action, which are shown by deficits in motor imagery. This study sought to test this hypothesis further using a mental rotation paradigm. It was predicted that children with DCD would not conform to the typical pattern of responding when required to imagine movement of their limbs. Participants included 16 children with DCD and 18 control children; mean age for the DCD group was 10 years 4 months, and for controls 10 years. The task required children to judge the handedness of single-hand images that were presented at angles between 0° and 180° at 45° intervals in either direction. Results were broadly consistent with the hypothesis above. Responses of the control children conformed to the typical pattern of mental rotation: a moderate trade-off between response time and angle of rotation. The response pattern for the DCD group was less typical, with a small trade-off function. Response accuracy did not differ between groups. It was suggested that children with DCD, unlike controls, do not automatically enlist motor imagery when performing mental rotation, but rely on an alternative object-based strategy that preserves speed and accuracy. This occurs because these children manifest a reduced ability to make imagined transformations from an egocentric or first-person perspective.

Procedural learning in children with developmental coordination disorder

Despite the fact that developmental coordination disorder (DCD) is characterised by a deficit in the ability to learn or automate motor skills, few studies have examined motor learning over repeated trials. In this study we examined procedural learning in a group of 10 children with DCD (aged 8–12 years) and age-matched controls without DCD. The learning task was modelled on that of Nissen and Bullemer [Cognitive Psychology 19 (1987) 1]. Children performed a serial reaction time (SRT) task in which they were required to learn a spatial sequence that repeated itself every 10 trials. Children were not aware of the repetition. Spatial targets were four (horizontal) locations presented on a computer monitor. Children responded using four response keys with the same horizontal mapping as the stimulus. They were tested over five blocks of 100 trials each. The first four blocks presented the same repeating sequence, while the fifth block was randomised. Procedural learning was indexed by the slope of the regression of RT on blocks 1–4. Results showed that most children displayed strong procedural learning of the sequence, despite having no explicit knowledge about it. Overall, there was no group difference in the magnitude of learning over blocks of trials – most children performed within the normal range. Procedural learning for simple sequential movements appears to be intact in children with DCD. This suggests that cortico-striatal circuits that are strongly implicated in the sequencing of simple movements appear to be function normally in DCD.

Characterization of the zebrafish matrix metalloproteinase 9 gene and its developmental expression pattern

Members of the matrix metalloproteinase (MMP) family are important for the remodeling of the extracellular matrix in a number of biological processes including a variety of immune responses. Two members of the family, MMP2 and MMP9, are highly expressed in specific myeloid cell populations in which they play a role in the innate immune response. To further expand the repertoire of molecular reagents available to study zebrafish myeloid cell development, the matrix metalloproteinase 9 (mmp9) gene from this organism has been identified and characterized. The encoded protein is 680 amino acids with high homology to known MMP9 proteins, particularly those of other teleost fish. Maternal transcripts of mmp9 are deposited in the oocyte and dispersed throughout the early embryo. These are replaced by specific zygotic transcripts in the notochord from 12 h post fertilization (hpf) and also transiently in the anterior mesoderm from 14 to 16 h post fertilization. From 24 h post fertilization, mmp9 expression was detected in a population of circulating white blood cells that are distinct from macrophages, and which migrate to the site of trauma, and so likely represent zebrafish heterophils. In the adult, mmp9 expression was most prominent in the splenic cords, a site occupied by mature myeloid cells in other species. These results suggest that mmp9 will serve as a useful marker of mature myeloid cells in the zebrafish.

State and input simultaneous estimation for a class of time-delay systems with uncertainties

This brief addresses the problem of estimation of both the states and the unknown inputs of a class of systems that are subject to a time-varying delay in their state variables, to an unknown input, and also to an additive uncertain, nonlinear disturbance. Conditions are derived for the solvability of the design matrices of a reduced-order observer for state and input estimation, and for the stability of its dynamics. To improve computational efficiency, a delay-dependent asymptotic stability condition is then developed using the linear matrix inequality formulation. A design procedure is proposed and illustrated by a numerical example.

Does elite competition inhibit growth and delay maturation in some gymnasts? quite possibly

Today, elite young gymnasts undertake training programs of progressive volume and intensity from an early age. For example, talented young female gymnasts often commence training at age 5 or 6 and train more than 20 to 30 hours per week year-round throughout childhood and adolescence. Despite the "normal" short stature of top-level gymnasts and the obvious health benefits of physical activity during growth, there is concern that elite level or those gymnasts involved in heavy training regimens may be at risk for adverse effects on growth and maturation. This concern has been the source of much debate in the literature and is complicated by the difficulties in distinguishing between the genetic predisposition to short stature and late or delayed maturation, and the effect of environmental factors such as nutrition and exercise that may influence growth and maturation. The effect of gymnastics training on growth and maturation is often reported as averaged data: an approach that does not identify individual growth patterns. Finding no difference between groups is not proof that there is "in fact" no difference. Accepting the null hypothesis without the appropriate critical review of both the methodological and statistical power to detect differences is a flawed endeavor. We believe there is compelling "circumstantial" evidence to build a case that preparation for advanced gymnastics competition may place some children and youth at risk of reduced growth and delayed maturation.

Delay control and parallel admission algorithms for real-time anycast flow

An anycast flow is a flow that can be connected to any one of the members in a group of designated (replicated) servers (called anycast group). In this paper, we derive a set of formulas for calculating the end-to-end delay bound for the anycast flows and present novel admission control algorithms for anycast flows with real-time constraints. Given such an anycast group, our algorithms can effectively select the paths for anycast flows' admission and connection based on the least end-to-end delay bounds evaluated. We also present a parallel admission control algorithm that can effectively calculate the available paths with a short delay bound for different destinations in the anycast group so that a best path with the shortest delay bound can be chosen.

Developmental language disorders and adolescent risk: a public-health advocacy role for speech pathologists?

Within the multi-disciplinary team concerned with child and adolescent development, speech pathologists are uniquely positioned to understand the nature and overall developmental significance of language acquisition in childhood and adolescence. Other disciplines contribute valuable insights about psychosocial development during the childhood and adolescent years. The field of developmental psychology, for example provides a large and convincing body of evidence about the role of academic success as a protective factor against a range of psychosocial harms, in particular substance misuse, truancy, early school leaving, and juvenile offending. In this paper, we argue that juvenile offending embodies the notion of "adolescent risk", but in Australia in particular, has been under-investigated with respect to possible associations with developmental language disorders and subsequent academic failure. We present findings pertaining to a sample of 30 male juvenile offenders completing community based orders. Performance on a range of oral language processing and production skills was poorer than that of a demographically similar comparison group. Our results confirm the need to conceptualize language within a broader risk and protective framework. We therefore emphasize the public health importance of early language competence, by virtue of the psychosocial protection it confers on young people with respect to the development of prosocial skills, transition to literacy and overall academic achievement. We argue that speech pathologists are best positioned to advocate at a policy level about the broader public health importance of oral language competence.

Design of linear functional observers for time-delay systems of the neutral-type

This paper presents the design of reduced-order linear functional observers for a class of linear time-delay systems of the neutral-type. The type of the observer proposed in this paper is without internal delay and its order is the same as the number of linear functions to be estimated. First, conditions for the existence of the reduced-order functional observers that are capable of asymptotically estimating any given function of the state vector are derived. Then, based on the newly derived existence conditions, a procedure is given for the determination of the observer parameters. The results derived in this paper include a range of linear systems and extend some existing results of linear functional observers to linear neutral delay systems. A numerical example is given to illustrate the design procedure.

A low-order linear functional observer for time delay systems

This paper presents an efficient technique to design low order state function observers for linear time-delay systems. Assuming the existence of a linear state feedback controller to achieve stability or some control performance criteria of the time-delay system, a design procedure is proposed for
reconstruction of the state feedback control action. The procedure involves solving an optimisation problem with the objective to generate a matrix that is as close as possible to the given feedback gain of the required feedback controller. A condition for robust stability of the time-delay system using the observer-based control scheme is given. The attractive features of the proposed design procedure are that the resulted linear functional state observer is of a very low order and it requires information of a small number of outputs. Numerical examples are given to demonstrate the design procedure and its merits.

Design of reduced-order observers for neutral time-delay systems

This paper presents a method for the design of reduced-order observers for a class of linear time-delay systems of the neutral-type. Conditions for the existence of reduced-order observers that are capable of asymptotically estimating any given function of the state vector are derived. A step-by-step design procedure is given for the determination of the observer parameters. A numerical example is given to illustrate the design procedure.

Body image and self-esteem : a developmental perspective

This study examined the relationship between different aspects of the body image construct and self-esteem among males and females in adolescence and adulthood. The respondents were 428 adolescent boys and girls, and 426 adult men and women. Regression analyses were used to determine the prediction of self-esteem by body image variables for different groups. The results demonstrated that body image consistently predicted male and female self-esteem, although the specific aspects of body image that were important differed between genders and different age groups. Body image was particularly relevant to the self-esteem of adolescent girls. The implications are discussed.