Development of the infant foot as a load bearing structure : study protocol for a longitudinal evaluation (the Small Steps study)

Background An improved understanding of the structural and functional development of the paediatric foot is fundamental to a strong theoretical framework for health professionals and scientists. An infant’s transition from sitting, through crawling and cruising, to walking is when the structures and function of the foot must adapt to bearing load. The adaptation of skin and other hard and soft tissue, and foot and gait biomechanics, during this time is poorly understood. This is because data characterising the foot tissue and loading pre-walking onset does not exist. Of the existing kinematic and plantar pressure data, few studies have collected data which reflects the real-life activities of infants with modern equipment. Methods This is a longitudinal study and part of the Great Foundations Initiative, a collaborative project between the University of Brighton and the University of Salford, which is seeking to improve foot health in children. Two cohorts of 50 infants will be recruited at the two sites (University of Brighton, Eastbourne, UK and University of Salford, Salford, UK). Infants will be recruited when they first reach for their feet and attend four laboratory visits at milestones related to foot loading, with experienced independent walking being the final milestone. Data collection will include tissue characteristics (skin thickness, texture, elasticity, pH and tendon thickness and cross-sectional area), plantar pressures and kinematics captured during real world locomotion tasks. Discussion This study will provide a database characterising the development of the infant foot as it becomes a weight bearing structure. The data will allow effective comparison and quantification of changes in structure and function due to maturation and loading by measuring pre and post established walking. Additional variables which impact on the development of the foot (gender, ethnicity and body weight) will also be factored into our analysis. This will help us to advance understanding of the determinants of foot development in early childhood

Trophic Relationships and Habitat Preferences of Delphinids from the Southeastern Brazilian Coast Determined by Carbon and Nitrogen Stable Isotope Composition

To investigate the foraging habitats of delphinids in southeastern Brazil, we analyzed stable carbon (δ13C) and nitrogen (δ15N) isotopes in muscle samples of the following 10 delphinid species: Sotalia guianensis, Stenella frontalis, Tursiops truncatus, Steno bredanensis, Pseudorca crassidens, Delphinus sp., Lagenodelphis hosei, Stenella attenuata, Stenella longirostris and Grampus griseus. We also compared the δ13C and δ15N values among four populations of S. guianensis. Variation in carbon isotope results from coast to ocean indicated that there was a significant decrease in δ13C values from estuarine dolphins to oceanic species. S. guianensis from Guanabara Bay had the highest mean δ13C value, while oceanic species showed significantly lower δ13C values. The highest δ15N values were observed for P. crassidens and T. truncatus, suggesting that these species occupy the highest trophic position among the delphinids studied here. The oceanic species S. attenuata, G. griseus and L. hosei had the lowest δ15N values. Stable isotope analysis showed that the three populations of S. guianensis in coastal bays had different δ13C values, but similar δ15N results. Guiana dolphins from Sepetiba and Ilha Grande bays had different foraging habitat, with specimens from Ilha Grande showing more negative δ13C values. This study provides further information on the feeding ecology of delphinids occurring in southeastern Brazil, with evidence of distinctive foraging habitats and the occupation of different ecological niches by these species in the study area.Peer reviewe

A LOFAR observation of ionospheric scintillation from two simultaneous travelling ionospheric disturbances

This paper presents the results from one of the first observations of ionospheric scintillation taken using the Low-Frequency Array (LOFAR). The observation was of the strong natural radio source Cassiopeia A, taken overnight on 18–19 August 2013, and exhibited moderately strong scattering effects in dynamic spectra of intensity received across an observing bandwidth of 10–80 MHz. Delay-Doppler spectra (the 2-D FFT of the dynamic spectrum) from the first hour of observation showed two discrete parabolic arcs, one with a steep curvature and the other shallow, which can be used to provide estimates of the distance to, and velocity of, the scattering plasma. A cross-correlation analysis of data received by the dense array of stations in the LOFAR “core” reveals two different velocities in the scintillation pattern: a primary velocity of ~20–40 ms−1 with a north-west to south-east direction, associated with the steep parabolic arc and a scattering altitude in the F-region or higher, and a secondary velocity of ~110 ms−1 with a north-east to south-west direction, associated with the shallow arc and a scattering altitude in the D-region. Geomagnetic activity was low in the mid-latitudes at the time, but a weak sub-storm at high latitudes reached its peak at the start of the observation. An analysis of Global Navigation Satellite Systems (GNSS) and ionosonde data from the time reveals a larger-scale travelling ionospheric disturbance (TID), possibly the result of the high-latitude activity, travelling in the north-west to south-east direction, and, simultaneously, a smaller-scale TID travelling in a north-east to south-west direction, which could be associated with atmospheric gravity wave activity. The LOFAR observation shows scattering from both TIDs, at different altitudes and propagating in different directions. To the best of our knowledge this is the first time that such a phenomenon has been reported

Tracking of an electron beam through the solar corona with LOFAR

© ESO 2018. The Sun's activity leads to bursts of radio emission, among other phenomena. An example is type-III radio bursts. They occur frequently and appear as short-lived structures rapidly drifting from high to low frequencies in dynamic radio spectra. They are usually interpreted as signatures of beams of energetic electrons propagating along coronal magnetic field lines. Here we present novel interferometric LOFAR (LOw Frequency ARray) observations of three solar type-III radio bursts and their reverse bursts with high spectral, spatial, and temporal resolution. They are consistent with a propagation of the radio sources along the coronal magnetic field lines with nonuniform speed. Hence, the type-III radio bursts cannot be generated by a monoenergetic electron beam, but by an ensemble of energetic electrons with a spread distribution in velocity and energy. Additionally, the density profile along the propagation path is derived in the corona. It agrees well with three-fold coronal density model by (1961, ApJ, 133, 983)

Assessments Related to the Physical, Affective and Cognitive Domains of Physical Literacy Amongst Children Aged 7–11.9 Years: A Systematic Review

Background Over the past decade, there has been increased interest amongst researchers, practitioners and policymakers in physical literacy for children and young people and the assessment of the concept within physical education (PE). This systematic review aimed to identify tools to assess physical literacy and its physical, cognitive and affective domains within children aged 7–11.9 years, and to examine the measurement properties, feasibility and elements of physical literacy assessed within each tool. Methods Six databases (EBSCO host platform, MEDLINE, PsycINFO, Scopus, Education Research Complete, SPORTDiscus) were searched up to 10th September 2020. Studies were included if they sampled children aged between 7 and 11.9 years, employed field-based assessments of physical literacy and/or related affective, physical or cognitive domains, reported measurement properties (quantitative) or theoretical development (qualitative), and were published in English in peer-reviewed journals. The methodological quality and measurement properties of studies and assessment tools were appraised using the COnsensus-based Standards for the selection of health Measurement INstruments risk of bias checklist. The feasibility of each assessment was considered using a utility matrix and elements of physical literacy element were recorded using a descriptive checklist. Results The search strategy resulted in a total of 11467 initial results. After full text screening, 11 studies (3 assessments) related to explicit physical literacy assessments. Forty-four studies (32 assessments) were relevant to the affective domain, 31 studies (15 assessments) were relevant to the physical domain and 2 studies (2 assessments) were included within the cognitive domain. Methodological quality and reporting of measurement properties within the included studies were mixed. The Canadian Assessment of Physical Literacy-2 and the Passport For Life had evidence of acceptable measurement properties from studies of very good methodological quality and assessed a wide range of physical literacy elements. Feasibility results indicated that many tools would be suitable for a primary PE setting, though some require a level of expertise to administer and score that would require training. Conclusions This review has identified a number of existing assessments that could be useful in a physical literacy assessment approach within PE and provides further information to empower researchers and practitioners to make informed decisions when selecting the most appropriate assessment for their needs, purpose and context. The review indicates that researchers and tool developers should aim to improve the methodological quality and reporting of measurement properties of assessments to better inform the field. Trial registration PROSPERO: CRD4201706221

EVALUATION OF THE DEVELOPMENT OF INDEPENDENT WALKING IN INFANTS USING INERTIAL SENSORS

Many studies have been observing infants at the onset of walking in order to evaluate the development of different strategies and coordination [Kubo, 2006, Roncesvalles, 2000, Yvanenko, 2005]. These studies regard most of the times small groups (<10) and only few studies observed longitudinally the evolution of independent walking (on 2 or 5 subjects) [Bril, 1992, Yvanenko, 2004]). To the authors knowledge these observations were always made using optoelectronic or video-based data. The use of wireless inertial sensors is more practical when aiming at the measurements of large populations. Moreover inertial sensors can be worn under the clothes facilitating the experiments with infants who are not distracted by markers and can freely walk and move in any environment. The aim of the present study is to observed longitudinally a large group of infants (>20) using inertial sensors over a 5-months period after onset of independent walking (period in which the most dramatic changes of maturation of many gait parameters occurs [Yvanenko, 2007]. This database will allow evaluating the changes in gait temporal parameters, postural stability and coordination at the beginning of independent walking. Moreover it will permit to evaluate when and how the development of pendulum mechanism occurs. The results presented here are only preliminary because they refer to five infants and only one test for each one

ORBITAL STABILITY ANALYSIS OF VOLUNTARILY ALTERED GAIT PATTERN

INTRODUCTION Falls are the primary aetiology of accidental deaths in persons over the age of 65 years in the United States [1]. The occurrence of fall is generally associated to an alteration of the stability in motion, although no consensus exists regarding how this stability characteristic can be quantified. Stability analyses of human gait range from mere observation by a trained physician or physical therapist to variability quantification of gait parameters, to the application of nonlinear techniques, designed to quantify the stability of a mechanical system. Among these, orbital stability quantified by means of Floquet Multipliers (FM) was found promising [2] in assessing how a periodic system (e.g. the neuro-muscolo-skeletal system during locomotion) responds to small perturbations (e.g. perturbations in control and/or environment determining gait pattern variability). This knowledge could lead to a better understanding of the control mechanisms determining the stability of a variable gait pattern, supporting the development of more effective rehabilitative procedures. Moreover, the eventual quantification of orbital stability exploiting a minimal measurement wearable set-up could contribute to the development of effective devices for the early detection/alerting of fall. The aim of the present preliminary study is to determine if alterations coming from voluntary changes in gait pattern during over-ground walking generate orbital stability alterations detectable from the acceleration data of a single inertial sensor. MATERIALS AND METHODS 5 healthy subjects (3 males, 2 females; age 27-35) performed an overground walking task at their preferred speed on a 20m hallway in 3 different walking conditions: normal walking (No), walking with narrower steps (N) and walking with wider steps (W). A portable triaxial inertial sensor (Xsens Technology, Enschede, Netherlands) was placed on the subjects, at the level of L5. State spaces were created using 5-dimensional delay embedding of the accelerations of the L5 sensor in the medio-lateral (ML), anterior-posterior (AP) and vertical (VT) directions [3]. Maximum FM (maxFM) were then computed for each time series. Acceleration data were normalized with respect to the height of the subjects. RESULTS MaxFM in the double support phase showed values < 1 for all the gait conditions and all the measurement directions. These values were lower than the mean values of the maxFM calculated through all the step cycle (Fig.1). In the N condition, maxFM values in double support phase resulted higher than in the other walking conditions, for all the measurement directions. Figure 1 - Values of maxFM calculated in the double support phase (Grey) compared to the mean values of maxFM through all the step cycle (Black) in the medio-lateral (ML), anterior-posterior (AP) and vertical (VT) directions, in the normal (No), narrow steps (N) and wide steps (W) gait condition. DISCUSSION MaxFM showed stable values (< 1) for all the gait conditions and measurement directions, indicating that all the subjects maintained orbital stability during the execution of the task. Lower values showed by maxFM during double support phase pointed out the capability of the method to identify the best stability condition of this phase of the step cycle with respect to the mean stability during the cycle. Higher values of maxFM of the double support phase in the N condition revealed a decrease in stability during that phase. In conclusion, acceleration data coming from one sensor placed at the level of L5 confirmed stability of walking normally and with voluntary changes in gait patterns in young subjects, but was just partially able to discriminate between the different walking condition. Future studies will involve orbital stability analysis of motor tasks performed by elderly or pathologic subjects