Time-delayed feedback control in astrodynamics

In this paper we present time-delayed feedback control (TDFC) for the purpose of autonomously driving trajectories of nonlinear systems into periodic orbits. As the generation of periodic orbits is a major component of many problems in astodynamics we propose this method as a useful tool in such applications. To motivate the use of this method we apply it to a number of well known problems in the astrodynamics literature. Firstly, TDFC is applied to control in the chaotic attitude motion of an asymmetric satellite in an elliptical orbit. Secondly, we apply TDFC to the problem of maintaining a spacecraft in a periodic orbit about a body with large ellipticity (such as an asteroid) and finally, we apply TDFC to eliminate the drift between two satellites in low Earth orbits to ensure their relative motion is bounded

Prevalence of hoarding disorder: A systematic review and meta-analysis

Currently there is uncertainty concerning the prevalence of Hoarding Disorder (HD) due to methodological issues in the evidence base. Estimates have widely ranged from between 1.5% and 6% of the general population. This systematic review and meta-analysis therefore aimed to summarise and reliably estimate the prevalence of HD by employing strict inclusion criteria and using studies with sufficiently large samples. A systematic literature search was conducted to identify all relevant prevalence studies. Inclusion criteria were studies that reported working age adult HD prevalence rates and had sample sizes of at least 1009 participants. Eleven studies met criteria (n = 53,378), had low risk of bias and were originally based in developed countries. A random effects meta-analysis was then conducted, with subgroup moderator analysis and meta-regression. The pooled estimated prevalence for HD was 2.5% (CI 1.7–3.6%) and subgroup analyses revealed that prevalence rates were similar for both males and females. Guidance on the manner in which HD is assessed in future prevalence studies is provided and the clinical implications of the results discussed

Do Playgrounds Help Develop Children’s Fundamental Movement Skills? Using Direct Video Observations to Investigate

Playgrounds are global environments that are purpose made for children and can offer a variety of opportunities for children to be physically active and practice their fundamental movement skills (FMS), which can lead to future physical activity and sport participation. Previous research highlighted that children engage in different types of physical activity (PA) depending on playgrounds apparatus and area. However, there is a paucity of research that investigates the link between playground features, structures, PA, and FMS. This study sought to assess the impact of different playgrounds on PA type PA intensity and the types of FMS completed. This observational study examined 29 (M = 10, F = 19) children’s behaviours on three different playgrounds. Video cameras were placed strategically across the three playgrounds to allow for footage to be captured and analysed using the Observational System for Recording Physical Activity in Children (OSRAC). One-way ANOVA was used to examine the different OSRAC categories across the three playgrounds. Climbing equipment (average 1217.10 s) was the frequently used type of apparatus, standing was the most commonly performed type of activity (average 377.60 s) and stationary movements whilst moving limbs were the most regularly (average 605.13 s) performed type of PA intensity. There were no instances of any throwing, catching, or kicking activities performed across the three playgrounds. Results suggest that public playgrounds do not facilitate more intense types of PA, nor object control skills due to a lack of suitable equipment

Wide-band information transmission at the calyx of Held

We use a mathematical model of the calyx of Held to explore information transmission at this giant glutamatergic synapse. The significant depression of the postsynaptic response to repeated stimulation in vitro is a result of various activity-dependent processes in multiple time scales, which can be reproduced by multiexponential functions in this model. When stimulated by Poisson-distributed spike trains the amplitude of the postsynaptic current varies considerably with the preceding interspike intervals. Here we quantify the information contained in the postsynaptic current amplitude about preceding interspike intervals and determine the impact of different pre- and postsynaptic factors on information transmission. The mutual information between presynaptic spike times and the amplitude of the postsynaptic response in general decreases as the mean stimulation rate increases, but remains high even at frequencies greater than 100 Hz, unlike at many neocortical synapses. The maintenance of information transmission is attributable largely to vesicle recycling rates at low frequencies of stimulation, shifting to vesicle release probability at high frequencies. Also at higher frequencies the synapse operates largely in a release ready mode in which most release sites contain a release-ready vesicle and release probabilities are low

Aerobically trained older adults show impaired resting, but preserved exercise-induced circulating progenitor cell count, which was not improved by sprint interval training

Older adults exhibit a reduced number and function of CD34 + circulating progenitor cells (CPC), a known risk factor for cardiovascular disease. Exercise promotes the mobilisation of CPCs from bone marrow, so whether ageing per se or physical inactivity in older age reduces CPCs is unknown. Thus, this study examined the effect of age on resting and exercise-induced changes in CPCs in aerobically trained adults and the effect of 8 weeks of sprint interval training (SIT) on resting and exercise-induced CPCs in older adults. Twelve young (22–34 years) and nine older (63–70 years) adults participated in the study. Blood was sampled pre and immediately post a graded exercise test to exhaustion in both groups. Older participants repeated the process after 8 weeks of SIT (3 × 20 s ‘all-out’ sprints, 2 × a week). Total CPCs (CD34 +) and endothelial progenitor cells (EPCs: CD34 +KDR +) were determined by flow cytometry. Older adults exhibited lower basal total CD34 + CPCs (828 ± 314 vs. 1186 ± 272 cells·mL −1, p = 0.0149) and CD34 +KDR + EPCs (177 ± 128 vs. 335 ± 92 cells·mL −1, p = 0.007) than younger adults. The maximal exercise test increased CPCs in young (CD34 +: p = 0.004; CD34 +KDR +: p = 0.017) and older adults (CD34 +: p &lt; 0.001; CD34 +KDR +: p = 0.008), without difference between groups (p = 0.211). SIT did not alter resting or exercise-induced changes in CPCs in the older cohort (p &gt; 0.232). This study suggests age per se does not impair exercise-induced CPC counts, but does lower resting CPC counts.</p

Characterisation of the immune response to type I collagen in scleroderma

This study was conducted to examine the frequency, phenotype, and functional profile of T lymphocytes that proliferate in response to type I collagen (CI) in patients with scleroderma (SSc). Peripheral blood mononuclear cells (PBMCs) from SSc patients, healthy controls, and rheumatoid arthritis disease controls were labeled with carboxy-fluorescein diacetate, succinimidyl ester (CFSE), cultured with or without antigen (bovine CI) for 14 days, and analysed by flow cytometry. Surface markers of proliferating cells were identified by multi-color flow cytometry. T-cell lines were derived after sorting for proliferating T cells (CFSE(low)). Cytokine expression in CI-responsive T cells was detected by intracellular staining/flow cytometry and by multiplex cytokine bead assay (Bio-Plex). A T-cell proliferative response to CI was detected in 8 of 25 (32%) SSc patients, but was infrequent in healthy or disease controls (3.6%; p = 0.009). The proliferating T cells expressed a CD4(+), activated (CD25(+)), memory (CD45RO(+)) phenotype. Proliferation to CI did not correlate with disease duration or extent of skin involvement. T-cell lines were generated using in vitro CI stimulation to study the functional profile of these cells. Following activation of CI-reactive T cells, we detected intracellular interferon (IFN)-γ but not interleukin (IL)-4 by flow cytometry. Supernatants from the T-cell lines generated in vitro contained IL-2, IFN-γ, GM-CSF (granulocyte macrophage-colony-stimulating factor), and tumour necrosis factor-α, but little or no IL-4 and IL-10, suggesting that CI-responsive T cells express a predominantly Th1 cytokine pattern. In conclusion, circulating memory CD4 T cells that proliferate to CI are present in a subset of patients with SSc, but are infrequent in healthy or disease controls

Campus copyright support from a university library

Presentation given on October 6, 2011 at the Missouri Library Association 2011 Conference in Kansas City, MissouriRGISIG/MACR

Scaling Success: Parental Perceptions of the Benefits of a 20-week Football Living-Lab Approach for Children Living with Cerebral Palsy

BackgroundLiving-lab approaches have effectively connected academic research with community needs but have not yet been applied to promote physical activity for children with cerebral palsy (CP). This study evaluated a 20-week football-based living-lab programme for children aged 5–10 years with CP, grounded in the principles of Football is Medicine and physical literacy.Methods A qualitative design was employed, involving seven one-to-one semistructured interviews with parents or legal guardians of programme participants. A deductive thematic analysis was conducted, and pen profile diagrams were developed to represent key themes related to physical literacy outcomes.Results Parents reported benefits across multiple dimensions of their children’s physical literacy, including improved competence, confidence, motivation and enjoyment. All parents observed enhanced social interaction. Six described the sessions as inclusive and community-oriented, while five felt the programme was personalised to their child’s needs. Three parents perceived the football activities as complementary to physical therapy, supporting physical rehabilitation. Participation also enabled parents to exchange strategies and engage more meaningfully in their child’s well-being.Conclusion The football-based living-lab supported the holistic development of children with CP, enhancing physical, psychological and social domains of physical literacy. Parental involvement further reinforced perceived therapeutic and community benefits

Simultaneous stabilization of MIMO systems via robustly stabilizinga central plant

In this note, a new formulation and solution to the simultaneous stabilization problem (SSP) is given. The new method is based on finding a central plant from a set of plants to be simultaneously stabilized. The theory of robust stabilization can then be applied to the central plant with a bounded perturbation, which encapsulates the plants to be stabilized, in order to solve the SS