Use of a modified SIR-V model to quantify the effect of vaccination strategies on hospital demand during the Covid-19 pandemic.

A novel compartmental model that includes vaccination strategy, permanence in hospital wards and tracing of infected individuals has been implemented to forecast hospital overload caused by COVID-19 pandemics in Italy. The model parameters were calibrated according to available data on cases, hospital admissions, and number of deaths in Italy during the second wave, and were validated in the timeframe corresponding to the first successive wave where vaccination campaign was fully operational. This model allowed quantifying the decrease of hospital demand in Italy associated with the vaccination campaign. Clinical relevance This study provides evidence for the ability of deterministic SIR-based models to accurately forecast hospital demand dynamics, and support informed decisions regarding dimensioning of hospital personnel and technologies to respond to large-scale epidemics, even when vaccination campaigns are available.

Centre of pressure parameters for the assessment of biomechanical risk in fatiguing frequency-dependent lifting activities.

Lifting tasks, among manual material handling activities, are those mainly associated with low back pain. In recent years, several instrumental-based tools were developed to quantitatively assess the biomechanical risk during lifting activities. In this study, parameters related to balance and extracted from the Centre of Pressure (CoP) data series are studied in fatiguing frequency-dependent lifting activities to: i) explore the possibility of classifying people with LBP and asymptomatic people during the execution of task; ii) examine the assessment of the risk levels associated with repetitive lifting activities, iii) enhance current understanding of postural control strategies during lifting tasks. Data were recorded from 14 asymptomatic participants and 7 participants with low back pain. The participants performed lifting tasks in three different lifting conditions (with increasing lifting frequency and risk levels) and kinetic and surface electromyography (sEMG) data were acquired. Kinetic data were used to calculated the CoP and parameters extracted from the latter show a discriminant capacity for the groups and the risk levels. Furthermore, sEMG parameters show a trend compatible with myoelectric manifestations of muscular fatigue. Correlation results between sEMG and CoP velocity parameters revealed a positive correlation between amplitude sEMG parameters and CoP velocity in both groups and a negative correlation between frequency sEMG parameters and CoP velocity. The current findings suggest that it is possible to quantitatively assess the risk level when monitoring fatiguing lifting tasks by using CoP parameters as well as identify different motor strategies between people with and without LBP.

Progression of muscular co-activation and gait variability in children with Duchenne muscular dystrophy: A 2-year follow-up study.

BACKGROUND: Duchenne muscular dystrophy is an X-linked muscle disease caused by dystrophin absence. Muscle weakness is a major determinant of the gait impairments in patients with Duchenne muscular dystrophy and it affects lower limbs more often than upper limbs. Monitoring progression of motor symptoms is key to plan treatments for prolonging ambulation. METHODS: The progression of gait impairment in a group of ten patients with Duchenne muscular dystrophy was observed longitudinally three times over a period of 2 years by computerized gait analysis system. Spatio-temporal parameters of gait, and variability indicators were extracted from kinematics, while lower limb muscles coactivation were measured at the baseline and at each follow-up evaluation. The 6-min walk test was used to evaluate functional capacity at each time session. FINDINGS: We found a significant increase in stride width and in both stride width and stride length variability at the 1-and 2-year follow-up evaluations. Furthermore, significant higher values in proximal muscle coactivation and significant lower values in both distal muscle coactivation and functional capacity were found at the 2-year follow-up evaluation. Significant negative correlations between muscle coactivation at proximal level and functional capacity and between muscle coactivation at distal level and gait variability were observed. INTERPRETATION: Our findings suggest that patients with Duchenne muscular dystrophy exhibit decline in functional capacity after 2 years from the baseline. Moreover, to cope with disease progression, patients try to maintain an effective gait by changing the balance dynamic strategies (i.e. increase in proximal muscle coactivation) during the course of disease.

Smartphone-Based Answering to School Subject Questions Alters Gait in Young Digital Natives.

Smartphone texting while walking is a very common activity among people of different ages, with the so-called "digital natives" being the category most used to interacting with an electronic device during daily activities, mostly for texting purposes. Previous studies have shown how the concurrency of a smartphone-related task and walking can result in a worsening of stability and an increased risk of injuries for adults; an investigation of whether this effect can be identified also in people of a younger age can improve our understanding of the risks associated with this common activity. In this study, we recruited 29 young adolescents (12 ± 1 years) to test whether walking with a smartphone increases fall and injuries risk, and to quantify this effect. To do so, participants were asked to walk along a walkway, with and without the concurrent writing task on a smartphone; several different parameters linked to stability and risk of fall measures were then calculated from an inertial measurement unit and compared between conditions. Smartphone use determined a reduction of spatio-temporal parameters, including step length (from 0.64 ± 0.08 to 0.55 ± 0.06 m) and gait speed (1.23 ± 0.16 to 0.90 ± 0.16 m/s), and a general worsening of selected indicators of gait stability. This was found to be mostly independent from experience or frequency of use, suggesting that the presence of smartphone activities while walking may determine an increased risk of injury or falls also for a population that grew up being used to this concurrency.

Wearable-based Temporal Parameters of Gait in Circuitous Routes under Dual-Task Conditions.

12 young adults were requested to walk along a circuitous path including turns, slaloms, stair ascending and descending, while wearing an inertial sensor placed on the back at the lumbar level. The path was completed under two conditions: with no additive cognitive task, and while performing a cognitive task and texting on a smartphone. Different temporal global parameters of gait were extracted from the inertial sensor data, to check for differences driven by the presence of the cognitive task. Regularity, durations, and temporal characteristics of gait resulted significantly affected from the presence of the additional task, and this effect was only in part due to a modification coming from the decrease in walking speed.

Correction: Gait parameters are differently affected by concurrent smartphone-based activities with scaled levels of cognitive effort.

[This corrects the article DOI: 10.1371/journal.pone.0185825.].

Gait parameters are differently affected by concurrent smartphone-based activities with scaled levels of cognitive effort.

The widespread and pervasive use of smartphones for sending messages, calling, and entertainment purposes, mainly among young adults, is often accompanied by the concurrent execution of other tasks. Recent studies have analyzed how texting, reading or calling while walking-in some specific conditions-might significantly influence gait parameters. The aim of this study is to examine the effect of different smartphone activities on walking, evaluating the variations of several gait parameters. 10 young healthy students (all smartphone proficient users) were instructed to text chat (with two different levels of cognitive load), call, surf on a social network or play with a math game while walking in a real-life outdoor setting. Each of these activities is characterized by a different cognitive load. Using an inertial measurement unit on the lower trunk, spatio-temporal gait parameters, together with regularity, symmetry and smoothness parameters, were extracted and grouped for comparison among normal walking and different dual task demands. An overall significant effect of task type on the aforementioned parameters group was observed. The alterations in gait parameters vary as a function of cognitive effort. In particular, stride frequency, step length and gait speed show a decrement, while step time increases as a function of cognitive effort. Smoothness, regularity and symmetry parameters are significantly altered for specific dual task conditions, mainly along the mediolateral direction. These results may lead to a better understanding of the possible risks related to walking and concurrent smartphone use.

Time-to-Boundary Function to Study the Development of Upright Stance Control in Children.

BACKGROUND: The development of postural control across the primary school time horizon is a complex process, which entails biomechanics modifications, the maturation of cognitive ability and sensorimotor organization, and the emergence of anticipatory behaviour. Postural stability in upright stance has been thus object of a multiplicity of studies to better characterize postural control in this age span, with a variety of methodological approaches. The analysis of the Time-to-Boundary function (TtB), which specifies the spatiotemporal proximity of the Centre of Pressure (CoP) to the stability boundaries in the regulation of posture in upright stance, is among the techniques used to better characterize postural stability in adults, but, as of now, it has not yet been introduced in developmental studies. The aim of this study was thus to apply this technique to evaluate the development of postural control in a sample population of primary school children. METHODS: In this cross-sectional study, upright stance trials under eyes open and eyes closed were administered to 107 healthy children, divided into three age groups (41 for Seven Years' Group, Y7; 38 for Nine Years' Group, Y9; 28 for Eleven Years' Group, Y11). CoP data were recorded to calculate the Time-to-Boundary function (TtB), from which four spatio-temporal parameters were extracted: the mean value and the standard deviation of TtB minima (Mmin, Stdmin), and the mean value and the standard deviation of the temporal distance between two successive minima (Mdist, Stddist). RESULTS: With eyes closed, Mmin and Stdmin significantly decreased and Mdist and Stddist increased for the Y7 group, at Y9 Mmin significantly decreased and Stddist increased, while no effect of vision resulted for Y11. Regarding age groups, Mmin was significantly higher for Y9 than Y7, and Stdmin for Y9 was higher than both Y7 and Y11; Mdist and Stddist resulted higher for Y11 than for Y9. CONCLUSION: From the combined results from the spatio-temporal TtB parameters, it is suggested that, at 9 years, children look more efficient in terms of exploring their limits of stability than at 7, and at 11 the observed TtB behaviour hints at the possibility that, at that age, they have almost completed the maturation of postural control in upright stance, also in terms of integration of the spatio-temporal information.

The Effect of Continuous and Discretized Presentations of Concurrent Augmented Visual Biofeedback on Postural Control in Quiet Stance.

The purpose of this study was to evaluate the effect of a continuous and a discretized Visual Biofeedback (VBF) on balance performance in upright stance. The coordinates of the Centre of Pressure (CoP), extracted from a force plate, were processed in real-time to implement the two VBFs, administered to two groups of 12 healthy participants. In the first group, a representation of the CoP was continuously shown, while in the second group, the discretized VBF was provided at an irregular frequency (that depended on the subject's performance) by displaying one out of a set of five different emoticons, each corresponding to a specific area covered by the current position of the CoP. In the first case, participants were asked to maintain a white spot within a given square area, whereas in the second case they were asked to keep the smiling emoticon on. Trials with no VBF were administered as control. The effect of the two VBFs on balance was studied through classical postural parameters and a subset of stabilogram diffusion coefficients. To quantify the amount of time spent in stable conditions, the percentage of time during which the CoP was inside the stability area was calculated. Both VBFs improved balance maintainance as compared to the absence of any VBF. As compared to the continuous VBF, in the discretized VBF a significant decrease of sway path, diffusion and Hurst coefficients was found. These results seem to indicate that a discretized VBF favours a more natural postural behaviour by promoting a natural intermittent postural control strategy.

Time to boundary function to assess upright stance in blind children.

The goal of this preliminary study was to assess the difference in postural stability between blind and sighted children using the Time to Boundary function (TtB). The experiment was conducted in twelve children (6-12 yrs), six of them had no visual impairment, and other six had congenital blindness. The participants stood on RotoBit force plate maintaining upright stance in static conditions. Each blind subject executed the task three times, each sighted subject executed the task six times, three with eyes closed (EC) and three with eyes open (EO). For all subjects each repetition lasted 30 s. The Centre of Pressure (CoP) coordinates, extracted directly from a force plate, are used to calculate four classical parameters (sway path, sway area, mean amplitude and mean frequency) and a predictive variable called Time to Boundary (TtB). The latter is the time it would take the CoP, given its instantaneous trajectory, to contact a stability boundary. Descriptive statistics were calculated for all parameters. Twoway ANOVA test was done considering the visual condition (EO, EC, BLIND) and the repetitions (RP) as a factor. In the first comparison (BLIND/EO) the results showed significant difference for all the parameters except for TtB. In the second comparison (BLIND/EC) the results showed significant difference only for TtB. In the third comparison (EO/EC) the results showed significant difference for all the calculated parameters. Therefore the TtB would be used to asses the postural control in children with blindness.

Can a Visual Biofeedback system based on predictive information improve postural performance?

The aim of this study is to assess if predictive information can be used to implement visual biofeedback (VBF) systems to improve postural performance. The Centre of Pressure (CoP) coordinates, extracted directly from a force plate, are used to implement two different realtime VBF, which respectively use current CoP coordinates (VBF(real_time)) and predictive stability information (VBF(predictive)). Predictive coordinates are calculated in agreement with time-to collision theory, using the real-time CoP components. In both VBF, subjects know if they are or are not in the stability area by an emoticon image displayed on the computer monitor. The expression of emoticon was smiling if the CoP coordinates were inside the area of stability, it was sad if the CoP coordinates exceed the stability area. Two groups of eighteen healthy young subjects performed the protocol in two different sequences: noVBF-VBF(real_time) and noVBF-VBF(predictive). Each condition was repeated three times, and its effect was studied by four parameters extracted directly from CoP coordinates (sway path, sway area, mean amplitude and mean frequency). Both VBFs determine a modification of postural parameters compared to the baseline condition (noVBF) with decrease of sway area and mean amplitude and increase of mean frequency. The comparison between the two VBFs shows significant difference for all parameters except for mean frequency. In particular, sway path, sway area and mean amplitude values for the VBF(predictive) decreased more than the same values for the VBF(real_time). The preliminary results may prove useful for the possibility of using this kind of VBF as a tool to improve postural performance.